swap Borge Warner 1::1 from 351pcm to 454pcm

Fire3456 wrote: Great information. From what I understand my transmission will bold up and I can change out the coupler but the shaft probably isn't long enough to take up the 1 inch difference?

Yep but............you're bound to run into unexpected issues that'll cost money to resolve and getting the 10-18 rebuilt would be my choice.

Fire3456 wrote: How could you tell that my tranny was a 10-17? (was that the number at the top that was worn off leaving what looks like a 17 left?    Being that my 10-17 is an inch shorter, will that effect the shaft placement in the Supra? Since my coupler is 4 inch would I have to use my shaft? Here was my initial thinking.   I thought If I could put my tranny in it for this year and take the 10-18 out and have it rebuilt. (Simple thought for a simple mind!) I'm taking measurements on the Nautique (shaft length. distance from coupler to boat bottom, etc ...to compare to the Supra) What did it cost you to rebuild your 10-18? Thanks Ken!

Yes for the 10-17 number. It would be a 10-17-004.

You can put the 10-18 coupler on the 10-17 (splines should be the same)

The Supra shaft probably couldn't slide an inch forward though without the prop hitting the strut or being too close to get a puller on it if you wanted to remove the prop. The chances of your SN shaft being the right length are.......probably not good but ya never know.

The rebuild was a DIY project, you should look at a manual in the reference section to see what's involved. A few special tools and a couple hundred in parts

Not a complete rebuild per se, but clutch pack replacement since everything else was good. You don't know what's wrong with the one you're looking at so who knows as far as price.

It sounds like you're thinking about buying this boat, so try knocking down the price by a thousand or so, unless it's already good and cheap

KenO

Your 10-17 is basically a later version of the 71c

The Supra with a 454 would have a 10-18 which is a later version of the 72c

The difference is that the 10-18 is beefier to handle more torque. It has 2 more forward clutch plates and 2 more clutch discs than the 10-17 and an extra reverse disc too

Overall length of the 10-18 is about than 1 inch longer than the 10-17 and the output couplings are different too   5 inch diameter for the 72c and 4 inch diameter for the 71c

They both have the same 1 to 1 ratio in FWD but in reverse the 72c is 1.1 to 1 and the 71c is 1.0 to 1 which really isn't noticeable but I thought I'd mention it.

I thought of doing this once for the same reason as you and in the end decided it was better to rebuild the 10-18 than try to use the 10-17.to handle that big boy torque of the 454.

And.....there's no e in Borg

KenO

Look at the tags on big block trans probably a 72-c while the one behind the 351. Is more likely a 71-c. 72-c is a bit bigger to handle 454 torque .Yes the 71-c will bolt up but can it handle power?