Can I use a TH350C core to build a TH350?

[team39763]

I needed to know if a th350C core can be used to build a regular th350?  I'm pretty sure my core is a 350C because of the wiring connector on the driver side and the A-1 C on the bellhousing.  Let me know if you know anything about that.  I'd appreciate it.  Thanks.

[VileZambonie]

Just build the 350c and wire up the lock up function then if you already have a good one. Having the converter lock under cruise isn't a bad thing.

[team39763]

Both transmissions are junk.  It's just that I can't pull my TH350 from the truck(not safely anyways) at the moment.  I found this TH350c core at the local tire shop.  Would it just be easier to grab a TH350(9") and yank my 6" tailshaft and have it put on the 9"? Is it even possible for me to take the tailshaft off with the trans in the truck?  What all would I need to pull with it to convert the 9" core to a 6"?

[DnStClr]

Not a transmission expert, but as I understand it you will have to remove just about everything inside the tranny with a 6" tail to replace it with a 9" tail. Better to do as Viliezambonie suggests.  Rebuild the 350C, but then you have to deal with shortening the driveshaft.
(had to edit this because of bad spelling)

[team39763]

I'm gonna just see if I can pull out my trans in my driveway.  Hopefully it goes well. Any suggestions on that?

[Lt.Del]

Rebuild the th350c.  I have one in my 79.  I ran a 12volt line to it with a toggle switch.  When driving over 35 mph, i flip the switch and watch the rpm's drop. 

As far as removing the trans, a good floor jack will work wonders.  Raise the truck up real high, like on ramps.  You will want to get the floor jack under the tranny and then be able to roll in out under the truck.


 put a wooden block on the floor jack and place it under the pan.  Remove the cross member, speedo, driveshaft.  Get a pan when you slip the driveshaft off for the trans fluid to drip in.
disconnect the battery because you will be playing with the red wire for starter...remove starter. Remove starter cable and the two bolts holding the starter in. It's heavy!

Be carefull with your radiator.  Once you take the cross member off, the trans must be supported into roughly the correct height as to not rock the engine on the motor mounts and tilt the fan into the radiator.  If you have hei distributor, be careful as to not tilt engine so distributor hits the firewall and breaks.

remove the gear selector (remove cotter pin and the gadget should slip out.)

remove the vacuum line for modulator. 

remove the trans fluid lines to radiator.

remove the nuts holding the flex plate to the torque converter.


Keep a rag handy.

with the weight of trans supported by bloor jack, remove the bell housing bolts.  The top two near the rear of intake manifold are a little tricky.  I use a box wrench from above on those.  on the side bolts, i use a long socket extension with swivel on the socket.

 
And if you don't have any jacks, this is what you do...... http://www.youtube.com/watch?v=Des0bPrllXA

[team39763]

LOL...those guys in that video are crazy. 

I think I'm gonna do it like you said SgtDel.  I will have access to a lift when I put the trans back in, but for right now I don't have a way to get it to the shop a 1/4mile away.  I thought about pushing it, but there's a few deep hills between here and there. 
I don't want to build the TH350C because I've read that you need a lockup type converter, and I just bought a non-lockup converter.  + the guys around my town  probably never heard of one.  Thanks ya'll.

[VileZambonie]

Why can't you just rebuild your TH350 then? I gathered that you were unable to rebuild the TH350 because it was not a good core. 

As far as swapping output shafts and tails you can do it but you need to remove the low reverse assembly (basically pull apart the whole trans)

[werewolfx13]

When I swapped the trans in the '84 I had, I went from a 350c to a 350 and really regretted it when gas prices started to climb..I went with the 350 because I needed a front pump for the 350c, and already had a brand new non lockup 350 converter, and was able to get a complete non lockup 350 with a good pump, actually the trans was still useable as is, but I rebuilt it anyway..lost 2-3 mpg on average on the highway.-

[team39763]

Here's the situation.  I had put a transmission in my truck, but decided that I didn't want to take any chances by running it.  I have the rebuild kit and parts aswell as a new converter for it.  The problem is, I don't have a way to pull the trans right now.  So I went out and looked for a core to rebuild instead.  I ended up finding a Th350C and at TH350(9"). I'm not too concerned with gas mileage, since this truck will only be used to drive my wife to work(1/4mile away), going around town(town is 1mile wide or less), and racing at the strip(it'll be towed there).  I think I'm gonna just try to pull the trans out in my driveway in the morning.

[Lt.Del]

Yeah, the converters are different.  I have experienced that you don't get the initial take off w/ the lock up tranny, as you do without--has something to do with the amount of fins, or size of the fins inside the lockup converter, whatever it is, there are less or smaller in the lockup converter to make room for the lockup feature. I think this robs the getty-up just a little.  But, the lockup feature is nice on the highway.

[VileZambonie]

The only major difference in the converter is the addition of the lockup piston. Aside from that it is essentially the same. Pulling out your trans is cake. All you really need is a floor jack and a few jack stands.

[Lt.Del]

Oh, i read somewhere that the converter is a bit smaller on the lockup 350c because of more junk they had to cram in there. I guess what i read was wrong.  Thanks for clarifying

 

[VileZambonie]

I've actually got two of them split open and a side by side comparisson they look nearly identical with the exception of the lockup piston clutch.

[werewolfx13]

I don't know about the insides, but a non lockup converter wont fit on a lockup input/pump shaft. The lockup shaft has a 1/2-3/4" nub on the end, and the lockup converter has a little dimple to allow the converter to fit all the way onto the shaft.