I've been looking for a TH350 "K" case (also called a HD case) to build a doubler behind (due to general shortage of TH400 203s). I'm not real happy about loosing the strength of my TH400, so I figure if I'm going TH350, I want the HD/"K" case.

Problem is, based on some feedback from people who are selling TH350s, maybe I don't know how to ID the TH350 "K" case.

I *thought* it had these characteristics.

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A visibly thicker and reinforced case. Hard to ID this without something to compare to beside it...
A "K" cast into the top of the main barrel of the case, behind the bell housing.
A 6 bolt cast inspection cover under the torque converter, rather than the 4 bolt stamped sheet metal version.
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So, am I confusing this with the TH400, or completely clueless. Can someone please give me a clue?

Don't know about the TH350, but those are all true for the 700 I pulled out of mine. FWIW, the S-10 one I put in did not have the same case.

Pete

as far as I know a 350 is a 350 (not including the 350-C thats just a 350 with a lock-up converter)

http://pics.montypics.com/alexisguy/2003-03-14/th_350_400.jpg

400 soak up to much HP for me. Do what I did and take the turbo 400 "sprag" and get it put into the 350 case (helps transfer torque). I also put TCI rev. pattern valve bodies-heat treated shafts-case exploder shield. I also machine for extra clutches in the 1'st & 2'nd gears (reduces slipping). I run this combo for 3 trucks now....never had a problem even up too 700HP.....

Thanks to everyone, especially Shaker for that extra build up info. That's what I was hoping for in the "Topic of the Week - Shifty business" thread.

Shaker, where would a TH350 newbie go to find out about those improvements and others?

Oh, BTW, for future searches, looks like some "K" cases do not have a "K" on them. Seems that some have "HD" cast in, or possibly other designators as well, all with the thick case. Based on other info I received on CK5, the only real way to be sure it to look for the mounting bosses cast in for the 6 *bolt* torque converter cover. One source of info even says that some thick cases came with the 6 bolt bosses untapped and a 4 screw cover in place! :eek:

Originally posted by BadDog
Thanks to everyone, especially Shaker for that extra build up info. That's what I was hoping for in the "Topic of the Week - Shifty business" thread.

Shaker, where would a TH350 newbie go to find out about those improvements and others?

I learned all about this stuff from my uncles who drag raced. A lot of the current stuff I picked up over 15+ years in the 4x4 world. I learned a few tricks from the guy who build the "Grave Digger" trannies down in NC. He does all my custom tranny work. In my last truck (Toyota SAS) on 35's with 4.11's could do a wheelie from a stop light...... :p :D

Ok, how about this then. Like I originally posted, I'm putting together a TH350/203/205 doubler in a K30 truggy behind a stock TBI 350 with 4.56 gears and 42" TSLs. I want to build the TH350 to take some punishment in the AZ rock gardens, lots of high temps and slipping the tranny. What is required? What would be a "good idea" but no "required"?

An HD sprag seems adviseable from what I've heard. You say use one from a TH400? What mods are required? Is that better (or the same?) than a 350 HD sprag? I don't think I'll be needing the extra clutches or hardened shafts because I'll never be putting that much power through it. No intentions of ever doing more than minor perf mods to the TBI 350 (dependability above all else, but a TBI cam for low rpm torque and an ECM tweak might be in my future), and the doubler gearing should help reduce most crawling torque loads.

You ought to check with www.TCIAUTO.com. They can tell you anything and everything about tranny's, and can reccomend what needs to be done to them for different applications.