TH375/NP205 Combo?

[JMD]

Hi all,
I need to find a way to mate my NP205 that was originally behind a TH350 to a TH400. I know Advanced Adapters sells a kit to do just that, but the $700 price tag is a bit steep, and that doesn't include the cost of machining the Tcase housing to accept the bigger input shaft needed for the TH400s 32 spline output shaft.

I have the opportunity to buy a TH375. From what I've read, a TH375 is basically a TH400 with a 27 spline output shaft from a TH350, so it should fit the NP205 input shaft just fine.

My question is, if I bought the TH400/NP205 adapter plate, can I bolt that TH375 to my NP205? The only issues I can think of would be the length of the 375s output shaft, and the oil seal in the adapter might not be the correct size. Can anyone provide some insight?

[52napco]

Keep your turbo 350....the 400 is cool but not worth the headache.A good 350 is hard to beat.

[JMD]

Yeah but that 350 won't live behind the 454 I have in the truck, already tried it once!

[kwmech]

The 375 output shaft is too long for the 4.5'' adapter, and there is not enough spline to cut down. If you insist on running a turbo 400 you'll have to get the correct parts and machine the 205 case for the 210 bearing

[CG]

I have a turbo 350 behind the 454 in my K20/2500 and it lives just fine. My truck belonged to Livrat before me. He has hauled and towed large stuff all over the country. Here in the NW its nothing but hills ... no problems. Over 80K on the drive train and it keeps on ticking. Small oil leak on the intake manifold, and a seal leak on the trans. Not at all bad considering what its been used for and how long its done it.

[Spf79]

Can you use the 700r4 spacer that is used when bolting a 700r4 to a th350 adapter?

[kwmech]

Originally Posted by Spf79

Can you use the 700r4 spacer that is used when bolting a 700r4 to a th350 adapter?

different bolt patterns between the 350 and the 400

[JMD]

Thanks everyone for the replies.

Originally Posted by kwmech

The 375 output shaft is too long for the 4.5'' adapter, and there is not enough spline to cut down. If you insist on running a turbo 400 you'll have to get the correct parts and machine the 205 case for the 210 bearing

I couldn't find any info on the TH375 output shaft length, thanks for the info. I'm fairly sure a rebuilt TH350 will live behind my stock (aka weak) 454, but I plan on adding power in the future and I only want to pull the transmission once. Since I have to pull the engine and transmission before spring anyway I figure it would be a good idea to put a capable transmission in there now.

I scored an NP205 with the 32 spline input shaft and a TH400 adapter attached for a decent price, so it looks like I'm committed to finding a TH400 now