73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: Jeff on February 06, 2010, 09:14:55 PM

Title: Engine/Transmission Swap
Post by: Jeff on February 06, 2010, 09:14:55 PM
I have a '74 C10, 2wd, step side, 6 cyl, 3 spd MT, heater only, no PS, no PB & no radio.  Cab & front clip have been restored.  My donor truck is an '86 GMC Sierra 1500 4x4, AT, PS, PB, AC (rock crawler/mudder truck) Allegedly, it has a 454 V-8 from a '70 Chevelle SS, a 700R4 AT, mated to an NP 205 twin-stick conversion, and a bunch of other expensive parts.....What I would like to do, is remove the current in-line 6 cyl eng, radiator, and manual 3 spd transmission from the '74 C10, and install my radiator, 454 engine, automatic transmission, floor shifter, complete dash & gauges from the '86 GMC.  *I'm wondering about the 700R4 tranny.  Since, I'm not going to use the transfer case, and the tail section will be shorter after I separate these two components, will a drive shaft (longer one will now be required) -slip yoke just slide over the tail shaft of the 700R4?
     In other words, I want to leave the '74 C10 as a 2 wheel drive truck, just a bigger engine with all the nice luxurious accessories,  and still utilize the automatic transmission that is actually shorter in length, and is intended for a 4x4 application?.  Sorry for the long post, English, grammar & punctuation is not my forte'.  Thanks in-advance for your info & comments. ;D
Title: Re: Engine/Transmission Swap
Post by: Irish_Alley on February 06, 2010, 09:31:16 PM
so you want to make your 4x4 tran a 4x2 just by removing the t case, if i understood you right it wont work that simple you have to rip your trans apart to do that as far as i know.  and if you could do it yes you would need a new shaft
Title: Re: Engine/Transmission Swap
Post by: Jeff on February 06, 2010, 09:43:59 PM
 Thanks for your quick response!!; Do you think I could deliver this to a reputable transmission repair shop, and pay for this alteration?  Also, I'm wondering if my 14 bolt rear-end will swap into the '74 C10?  If it can, that will only leave me with a front axle, custom winch-bumper, and a transfer case to get rid of. 
Title: Re: Engine/Transmission Swap
Post by: Blazin on February 07, 2010, 01:03:46 AM
The dash is not going to work its to far a year spread. The output shaft is different in the 4x4 trans. You need a 2 wheel drive output shaft, and a 2 wheel drive tail shaft housing. My opinion it would be less headache if you just found a 2 wheel drive trans, and had it rebuilt.
Title: Re: Engine/Transmission Swap
Post by: Captkaos on February 08, 2010, 04:35:29 PM
Or just buy a 2WD trans since the shop is going to have to pull everything apart to convert the output shaft that you don't have and if you are going to dismantle it I doubt they will put it back together like it came and warranty anything, I wouldn't.

The dash will work if you use the cluster with it, but you will have to change the wiring as the 74 has AMPS and the 86 has volts.
Title: Re: Engine/Transmission Swap
Post by: Jeff on February 09, 2010, 04:52:06 PM
Well, I've got some good news (I think?).  I called a local transmission shop, the owner said he had the required output shaft.  He said if I brought the transmission & torque converter to his shop, he would retrofit it, rebuild it, and install it in my '74 C10 for $1500.00.  I forgot to ask about the warranty.  I priced a kit from PATC for around $932.00 (including the torque converter).  At any rate, I've got all the necessary equipment (TV cable, etc.) to implement it's installation to the 454/Edelbrock carb.
     I bought a "universal"/GM wiring harness.  I plan on completely gutting and removing my entire '86 dash, gauges, A/C-Htr controls, duct work, etc., and installing it in the '74.  I know it will be a pain-in-the-posterior, but the desire for A/C & nice gauges feeds my ambition and determination for success!.  As a matter of fact, I'm removing the old 6 cyl eng, 3 spd man trans, and old wiring.  The step side bed will be the last phase of this restoration/rebuild.  Thank you very much for the info regarding Amps vs Volts, just don't quite understand what message you're trying to convey.  Sorry, I veered-off the initial topic of my post, I really appreciate your help.  I will post photos, when I return back to my residence.  Currently, I'm in the metro Wash D.C. area (I'm sick of snow :P).