C6 Vibration after accidental reverse at low speed.

[FomocoLoco72]

I tried to search this but I didn't see the "idiot put the truck in reverse" link anywhere.
Heres the setup at the time of my stupidity
1972 F100 Ranger Long bed 390 w/C6 (100% stock) towing a 6000lb boat/trailer. Tows like a champ.

Slow speed roll in first (<5mph) went to engage neutral, went to far and she went into reverse for just a second. No loud noises, no bangs no tires screeching. Now I have an intermittent rumble almost like a really bad alternator bearing that seemed to be coming from that area but when I dropped the belts everything was fine. She towed to the lake yesterday and back rumbling occasionally but I feel like it is not happy at all now that I can drive it unloaded. Any idea what I may have hurt/killed? She still shifts good and seems to drive okay but I am highly suspicious Its been <25 miles. I have never had one of these apart and I understand its only a guess but could I have hurt some expensive hard parts? I will be doing the rebuild as long as I can get away with mostly soft parts. AND is there anything I should look out for?

[cep62]

I would start by checking the U joints and maybe listen to the rear axle . those C6s are pretty tough.
I've plowed snow for years and every once in awhile I've misjudged my timing and banged the gear too fast , with out any ill affects.
But . Anything can happen.

[FomocoLoco72]

thanks I hadn't thought about the drive-line/axle. I guess it could be a u-joint or the center bearing, I don't think it would have hurt the diff.