360 F1

I have rebuilt or replaced about half a dozen 360 transmissions with worn out syncronizers. That fits the description of what you are experiencing. It is in my opinion a function of that substandard gear oil they are being handsomely paid to tell you to use.

If you have a good shop you can get the syncronizers replaced for less than a used unit will cost and then you have new, not unknown used. It will take a few rather expensive special tools to do the job so find someone who has done 360 transmissions before. They are a bit different than the other gearboxes.

 

rifle, do you have a recommendation on a good gearbox oil. I've used Royal Purple, Mobil One, and Redline in other cars.

 

I suspect any of them would be OK but I use Redline.