Hot Boat,
You are correct. You can do that, but make sure there are no nicks in the FWD gear. They can and will cause damage to the new pinion gear. If there are no nicks in the FWD gear, go ahead and use it in the REV position. I have done it before without problems. But the FWD gear must be in good condition. If you dont want to take a chance. i do have a single gear that looks like it has 20min of run time on it that I would be happy to sell you.
Another suggestion, break in the drive for 25hrs before you run it hard. I like to change oil at 5hr, 15hrs, 25hrs. It takes that long for the gears to break in. During that process there is metal in your oil flowing through perloaded tapered bearings.
The cryo treatment I do includes a polishing treatment that helps alleviate that problem of metal produced from break in.

If you would like to discuss your gear swap in more detail, feel free to give me a call.. Be happy to share my experience on the subject.

Dick
616-403-1006

Thanks Dick , thats what I was hopeing you would say. My drive is at a friends house. Once I have a chance to stop by and inspect everything more closely I'll let you know.

I would love to get away with just replacing the pinion. If thats all I need to do, when would I cryo the gears. Do I let the new pinion break in for a few Hrs or do I just treat them as they are??????

Either way, treating them before you run them, takes the rough finish off. But running them for a few hours and then treating them makes for a nice smooth finish. And I am guessing that stressing the gears a bit doesnt hurt either. But I have not tired it each way. I know the one set that was used and treated look almost like when they were installed after the treatment. Take a look at the thread I started for "Treated Gears"..

Dick