Th350c major leak & future behind an ls?

[Taylorb27]

So the th350c in my 84 c10 decided to leave a nice oil slick about 4 blocks to my house. Looks to be leaking from inside the bell housing as it’s leaking from my starter and somewhere on the driver side. Guessing the oring seal for the TC or a front seal? Anyway this is jumpstarting my LS swap project, I told myself I’d drive it stock until something happened.
I know I read somewhere that the 350c trans is not as strong as a regular 350 but I’d like to at least have lock up, so how would it do with a 5.3 that’s got a typical 220 cam? The trans will be rebuilt, have a higher stall converter, and have a tru cool 40k cooler or something like it.
Main reason for sticking with the trans I have is because the standalone ls harness I have is for a non electric trans set up.
I could try to find a 700r4 I guess for overdrive but I’d rather avoid setting up the tv cable even though Im using drive by cable on the 5.3

whatever input you guys have just shoot it my way! Thank you!

 

[HotRodPC]

Puked out the front seal !!!. Since you already have the 350C, I'd keep it. It is just a hair weaker in the front shaft, otherwise the same as Th350. Chances are if you'd break the Th350C shaft, you probably would have broke the Th350 shaft too. I've broke many Th350 shafts of course, that's form racing and far from stock power. When you can build your own, you don't much care how often you break it but I know I couldn't afford a Chromolly input shaft or I'd have solved that problem.

 

[Taylorb27]

Puked out the front seal !!!. Since you already have the 350C, I'd keep it. It is just a hair weaker in the front shaft, otherwise the same as Th350. Chances are if you'd break the Th350C shaft, you probably would have broke the Th350 shaft too. I've broke many Th350 shafts of course, that's form racing and far from stock power. When you can build your own, you don't much care how often you break it but I know I couldn't afford a Chromolly input shaft or I'd have solved that problem.

awesome! I’ve never dealt with a c before so wasn’t sure how much of an issue the tc seal was. Probably just going to order a good “stage 2 or 3” blah blah rebuild kit, do a trans go kit and try to find a 2200 stall converter that will work with lockup.

thanks for the help!

 

[HotRodPC]

the lock up only saves about 300 rpm but it does add up. The best part of lock up is the transmission running cooler when the covnerter is locked up on those longer freeway drives. Helps it last longer.

 

[Matt69olds]

The 350 and 350C are almost identical. Unless you have a really stout LS, it will be fine. I’d install a shift kit, and if your rebuilding it have the direct piston machined for a 5 clutch (the factory only has 4).

Due to the input shaft design, the 350C is a little weaker than a 350. But it’s still much stronger than the 4L60E used behind the LS originally.

 

[HotRodPC]

The 350 and 350C are almost identical. Unless you have a really stout LS, it will be fine. I’d install a shift kit, and if your rebuilding it have the direct piston machined for a 5 clutch (the factory only has 4).

Due to the input shaft design, the 350C is a little weaker than a 350. But it’s still much stronger than the 4L60E used behind the LS originally.

Exacdtly. People give the 350C a bad wrap, but that's usually keyboard warriors and pass on bad info for more bad info. As we've both said now, the input shaft is a bit weaker to make use of the lock up converter. IMO, the lock up converter has more to offer in keeping the trans cool at freeway speeds when locked up that the bit of weaker input shaft and certainly transmission as a whole is stronger and more reliable along with tolerate more abuse than any 4L60-E ever will.