Recommendation on turbo 350 gasket kit

[SRU1436]

My transmission leaks, as expected because it’s all original and never rebuilt, the transmission works fine other than leaking. My truck is an all original 72 c10, with 76k mile 350 and turbo 350. I want to try and stop most if not all leaks on the tranny, so I’m looking for a gasket kit. I found the following so I’d like a recommendation, or if anyone has other recommendations for a gasket kit. My pops has a lift so we will be using that, and I don’t want to drop the transmission. Thanks for the help/recommendations.

https://www.classictransmissionsolut...-transmission/

[RustyPile]

Over 60 dollars spent on this seal kit and only about 1/3 of those pieces can be installed with the transmission in place.

The "in car" seal and gasket pieces can be purchased separately for about 10 - 12 bux..

[AussieinNC]

Ok, here is my recommendation based on 40 years of auto trans rebuilds...

Pull the transmission and do it right...grab a rebuilt convertor and a full rebuild kit including clutches and steels.

There are a ton of videos available to guide you thru the rebuild process plus several threads on this forum to guide you.

Why am I recommending pulling the trans?

Apart from the pan gasket and selector shaft seal, the main leaks in these is almost always the pump to case O ring and gasket, the bolt holes seal washers and the extension shaft seals and bushes. Always replace the pump case bush and rear case bush.

The speedo cable bullet will need O rings and seal on the speedo driven gear.

If you are not comfortable doing this yourself, find a local shop for the job.

Just my 2 cents worth.

[Dead Parrot]

When I did an engine swap many years ago, my transmission(TH350) was leaking. Worked fine but left a mess under the truck. Talked to a local shop. He said he could replace 3 of the 4 main seals without major disassembly. The 4th one is apparently very buried. Price included a new pan gasket/filter and the other minor outside seals/o-rings/etc. I had already tried replacing the tail shaft seal but that did little to stop the leaks.
Pulled the trans with the motor. The shop did their thing while I was transferring parts from old motor to new and doing some engine bay clean up. Reassembled everything and installed. Fixed the leak problem. Still leaks less today then before the new seals. About a 140K miles and 20+ years later.

Two of the seals(one of them is the buried one) require front access.

Another vote for drop the trans and do a complete (or near complete if you skip the buried seal) job. Plus you can do a good cleaning while it is out. Ask a shop what they will charge if you bring the trans in. Might be less then you expect. IIRC my cost was under $100, but it was 20+ years ago.

[AussieinNC]

The two "buried deep" seals are the pump sealing O ring around its perimeter, and the paper gasket between the oil pump and the case.

These are fairly simple transmissions, hence their longevity...I would fully reseal it and not lose sleep in the future.

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[Accelo]

Lots of the leaking can be sourced to the crappy "O' ring(s) on the dipstick tube.
Updating this to the newer top hat style tube and seal solves a lot of issues.
Often this leak looks like a pan gasket leak and it is not.

Also replace the plastic speedometer gear, and associated seal, as they are all worn and will not seal with a large groove worn into them. Pan gaskets don't typically leak if the correct composite gasket is used, without sealant, and torqued correctly. And the pan hasn't been dragged across rocks, it has to be flat. It appears to me the kit has all you need including the "Good" gasket. Clean the surfaces with solvent and install the pan gasket dry.
Good luck.

[CanadianNascar]

All very good advice, pan gasket, dipstick tube oring or hat, kick down cable and/or new oring, converter seal, and pump gasket.
Also replace the shift shaft, it can have a groove or nick which will still cause leakage.
https://www.summitracing.com/parts/sox-35801-02k

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[SRU1436]

Thanks for all the advice, I’m not ready to pull the transmission just yet. So I may just change a couple of the easy ones and see what happens. When I rebuild the motor down the road I’ll do the transmission at the same time.

[vince1]

I have bought my parts from Northwest transmission or Fatsco. The only autos I went through were a Honda 2 speed many years ago and a few years ago a couple of different BorgWarner M35's for Ramblers.

I have the same story, my Rambler is leaking and I'll get to try out how good my rebuild is. I put the leaker in over 40 years ago that I got from an auto wrecker and it has always worked good.

[AussieinNC]

Many moons ago I started out rebuilding Powerglides, Borg Warner 35;s, C4 and C6 and Torquflites....ahh the good old days.

Cant believe that was 50 plus years ago....heck, does that make me old?