Transmission replacement or upgrade?

[The Swed]

The current transmission is leaking but still running well and I'm thinking about swapping it out for another 350TH then it dawned on me that a 400TH or 700R maybe the way to go.

Thanks for all the input!

[Mike C]

If it were me, I'd fix the leak and drive it. Unless it was used to regularly haul pretty heavy then maybe a TH400 would make sense.

But if I was going to spend any money on an upgrade, it would be a built TH200 4R. I hate the 1-2 shift on a TH700R4, but the 200's gears make perfect sense with a 3.73 rear. And you can use your original driveshaft. Only mod is to move crossmemeber back.

[big bad orange]

I agree there is no point in using a th400 for normal use behind a stock engine unless you are hard on it. The cheapest route would be to pull your th350 reseal it (and what ever else it needs at this time) then put it back in. A 200 r4 would be the easier way to get overdrive but to be honest other them buying them new i have not seen them in the junkyards much.

[Hook'em]

That looks like a pretty dramatic leak. Have you found the problem? I had something similar and it turned out to be the speedometer bullet that connects the speedo cable to the transmission. I was able to fix it with about a hour of time and $20 part.

[The Swed]

It gets worst as it sits of over time then stops. Almost as if it pooled up some where then slowly drains out over four days or so.

[Eddie H.]

As the truck sets for a few days, some of the trans fluid will drain back out of the torque converter into the pan, raising the fluid level in the case. Your problem could be as simple as a leaking dipstick tube o ring, selector shaft seal, etc. I would clean everything off, then try to pinpoint the source of the leak before doing anything else.

[Mike C]

I'd worry about what looks like a leak on the right front tire, too....

Some output yokes have an air bleed hole and some don't. Different trans setups require that and sometimes on rebuild/replace they will use the wrong yoke.

Then, as mentioned, the fluid in the converter leaks down raising the pan level. It can run from the dipstick o-ring, the pan gasket, sometimes speedo drive housing, or the yoke seal or that bleed hole in the yoke.

[The Swed]

Yeah the brake wheel cylinders are all leaking and that's a different thread but a great catch on your part! Here's another clue... :/

[Mike C]

Yeah, I own lots of old crap...