My 70 Cuda 383 with a 23 spline 4 speed had a lot more whine than it should've had and front seal was leaking badly. Pulled it out and took it to a reputable shop to diagnose and repair. Apparently it had sat for long enough of a time that the gears above the oil line had corroded enough to be pitted very bad. Weber and Passon didn't have my all of parts in stock but shop found that Pro-Gear in California said they did. I could either get only the damaged gears for $450 and gamble on bearings or get the complete gearset with everything for $1,280 including overnight shipping and labor. So I went with everything.
1. Gear set comes and its an 18-spline instead of 23.
2. Next day its the correct gear set but no bearings or seals.
3. Next day everything comes, but one bearing is wrong.
4. Next day finally have everything.
Take it out for test and the whine is 75% gone and is level of sound that its suppose to be. Decide that its time to REALLY go through the gears since engine should have enough break in miles to do it finally. Frikkin clutch is slipping after it hits 3,000rpm !! Check free play and there is 1" of pedal travel.
Gonna take it easy and pull the tranny back out and change clutch later this summer. Time to just enjoy. (for now)