84 K10 Silverado 305 700R4 with 10 bolt rearend questions. Need opinions

[txhuntingguide]

Just purchased my 13 yr. old a 1 owner with 93K original miles on it.  We are gonna go through the whole truck and restore it. Body only has one rust spot and its in the right front wheel well. We have 3 yrs. and 10K-20K to do everything. IT came with 31X10.50 tires stock. He wants to put 32 or 33" tires on it.

How do I find out what gear it has without pulling cover and counting it. Are there any numbers I am not finding to tell me ?
What gear would you want for decent fuel economy with enough low end to still be a 4X4 running a 33" tire?
What are your thoughts on the 10 bolt rear ends in a 4X4 ?
What are your thoughts on the 305? IT starts and runs good. Just low on power.
He wants to go with a 350 or 383 for more power! IF we do I am thinking no more than 300 hp. IF we do that I may want to go TBI of MPFI, thoughts on this as well.

[cvbear]

Congratulations on the new project!  Your timing is good, kudos for getting such an early start.  I did something similar with my son, but did not start until he was 15 and he turned 16 before I got all of the projects done on it that I wanted.  As I went along more projects kept coming up!  If you want to do more than just maintenance on the motor, I suggest you consider putting in a more recent fuel-injected motor like an LS.  It will cost $ and require some maintenance, but I wish I had gone that direction since I think the drivability would be better.

[Irish_Alley]

for a dd you dont need anything more than a 10 bolt. if you want to go off road then abuse it yeah upgrade. also some gear ratios are limited to what axles you want. in a 4x4 k10 you should be around 3.23. there is a rpo code in the glove box but its only good if its the original axles.
the 305 will get you from point a to b, changing gears on a 305 will help with the take off. now im run 38s+ i would go for 3.73 or 4.10s but i only get 9 mpgs cuase my trans is limited to a 1:1 ratio. if i had od i think (dont know just hope) i could see 12s on a good day. you just need to figure out what tire size you want axles and then ratio. with 33s you might need a lift.

also welcome from maryland

[bake74]

     Welcome txhuntingguide to the site.  With 33" tires you should at least go with a 2.5" lift if not 4".  Stock height and 33"'s will rub if you go into a parking lot or such at a angle and the truck leans to one side.
     I do not think a 16 year old needs a 383, but I think that if you leave the 305 you both would regret it and probably change it out after a year of driving it.  There are kits to add EFI to carburetor trucks for less than 2 grand which in my opinion would give you the best MPG option, less than doing a newer LS swap.
     If it is a automatic I would suggest putting in a 700R4 trans so you have overdrive.  There is a way to be able to lock up the TCC without the comp., see this article for some reading tips.  If it is standard then you have a couple options if you want overdrive.
     If you do go with a OD trans, with 33" tires 3.73:1 will give you a comfortable 2000-2003 ish cruising range in OD.  There are calculators to determine what speeds in what gears you will be going.
     Good luck with the project, father & son projects are the best.

[roundhouse]

Your 84 probably came with a 700R4 OD
The 305s are gutless but usually last forever
But you don't want huge HP for a teenage boy.  That's not a good combo.
One way to determine the axle ratio is to jack up the axle and get both wheels off the ground
Then mark the driveshaft with some chalk or something
And mark one of the wheels
And while one person turns the driveshaft  and counts the number of turns it takes to make one complete revolution of the tire

It will be close to one of the available ratios for your model year if it's still stock. 
If you only jack up one tire the result will not be accurate

You don't need to spend anywhere near $20k

good used 350s are a dime a dozen.   Not hard to find

A few months ago we bought a 79 stepside K-10 for my 15 yr old
And we added TBI from a 90 model first thing
Paid $200 for the complete setup off a running engine that had a cracked block.

Spent about $200-250 on other parts
New sending unit in tank.   New frame mounted fuel pump.  New hoses  etc etc

Lots of info for retrofitting TBIs on binder planet.com

With all the defective design problems with the MFPI I'd probably avoid those

An early Vortec 350 will have plenty of power and none of the issues of cooked injectors like with the later version that had the injectors near the cylinders


We areWorking on swapping InA/C also


I think 33s will fit ok without any lift
33s will fit on just about any full size truck without a lift


Might have to trim a little from the bottom corner of the fender. Depends On the rims offset. A little rubbing isn't going to hurt anything as long as its not rubbing on something sharp that can cut the tire.     If it rubs a little on the inner fender or frame it's harmless

You will lose 1/2 mpg for every inch you go up in tire size.   And another 1/2 mpg for every inch on lift

[bake74]

I think 33s will fit ok without any lift
33s will fit on just about any full size truck without a lift

      My 74 with 33" tires and stock height, even with new bushings and cab mounts would rub slightly at uneven angles, like entering a parking lot sideways with a dip between the road and parking lot (I have 33x12.5x15 tires, so if you have skinnier tires you might get away with it).  If your cab mounts or bushings were worn a little it would rub even harder.  This I know from experience, the negative arch of the front springs are really a plague on our trucks and GM should never have made them in my opinion.

[txhuntingguide]

This is good info guy's. Maybe we should stick to 32X11.50. We are going with BFG All Terrains. This truck does have a 700R4. I was leaning toward a Vortec 350. The TBI retrofits look to easy to be true. What are the knocks on doing it ? The 5.3 LS engines are appealing and have heard they prove in better fuel economy. But, there is a big $ difference. The 10-20K is including full body off restoration over 3 years or so. Not gonna dump that into the drive train.
Our whole family hunt and fish as much as possible. He wont be doing any heavy pulling just a show trailer with a few show hogs a few times a year. Not to many long trips probably 120-150 mile round trips every weekend hunting in the fall and then regular kid stuff during the weeks. The ranch is mainly sand hills and then mesquite flats. Roads are mainly sand. Low end torque would be better for take off and hunting.
My first vehicle was a 79 3/4 ton with a 454, granny low and 3 go. Dad and I put a 4 bolt 350 in it with an aluminum intake and 2 barrel Rochester, Headers, HEI ignition and left the tranny and gears alone. I drove it to college and for 4 years with a little advance timing and good maintenance got 15-17 mpg!!! Back when the speed limit was 55.
I want to build this truck dependable, easy starting, with decent fuel economy keeping 75 mph speed limit in mind. It cant be a dog due to hunting and fishing out of it but, he does not need a hot rod.

[roundhouse]

Check out binderplanet for TBI swap Info


We pulled one from a 90 model and put it on a 77 ish K-10. Took a couple weekends to do it
It's not rocket science

Sorting out the wiring harness to eliminate the wires you're not going to use takes about as long as the Install

I'd reccomend finding a complete working system on a donor truck and remove it yourself
Take pictures.  Bag and tag the bolts screws and small parts

We got one for $200 and heard it run before we pulled It

You could probably find a running TBI vortec in a wrecked Yukon or something  and grab the whole engine
For a couple hundred more

[Irish_Alley]

You will lose 1/2 mpg for every inch you go up in tire size.   And another 1/2 mpg for every inch on lift

if this was true on my 79 with 40 or 38s and 6+3" of lift i would be getting 19-20 mpgs. might have to take off my lift for this but im not one to trim fenders on a restoration 

[bake74]

You will lose 1/2 mpg for every inch you go up in tire size.   And another 1/2 mpg for every inch on lift

     Corrected, miss read first time.

[Irish_Alley]

his one way he says -.5 for tires and -.5 for the lift. if you read it the other way it says -.5 for the tires and +.5 for the lift.  if you read mine it can be taken either way also. but what i was saying on my 79 as it sits now i get 9-10. so iff i take the lift off and put stock tires i would be getting 19-20

[roundhouse]

Like I said.   You generally lose 1/2 mpg for each inch of lift over stock  And lose another 1/2 mpg for each inch of tire size increase over stock

Not carved in stone    But it's a general guideline
Installing A 3"lift and and increasing tires from a 28" to a 33" will cost ya somewhere around ~5 mpg

At least that's been my real world experience

[txhuntingguide]

OK guy's I found an '98 2500 Single cab 2WD with 230K miles, automatic, with Vortec 350 running and drives. I can get it for $1,000 doesn't smoke. What do yall think?

[bake74]

OK guy's I found an '98 2500 Single cab 2WD with 230K miles, automatic, with Vortec 350 running and drives. I can get it for $1,000 doesn't smoke. What do yall think?

     Are you planning on swapping out engine only ?  You are going to need to buy an adapter to mate the trans you have now.
     I would do a compression check first with that many miles.  If it checks out I think you have a good deal, then you can try to sell the body and rest to make up some of the money.

[txhuntingguide]

Hey Bake74 thanks for the info on this build planning. The 98 is a 2 wheel drive, will the Tranny's be the same. Can you just swap tail housings? I own a portion of an A/C company. We have 2 - 2005 and 1- 2006 2500 Express vans all with 4.8 engines and about 200K on them we are going to be getting rid of this year. They are all daily service vans that run great and don't use oil, about 50% of those miles in town. I can take my pick of these vans for about $600 each. Would the 4.8 motor and all be a better way to go for tuning and all?