The rebuild info I have [ fromwww.transonline] indicates there were b2 seal and bushing/sleeve mods right up to 722.369s [ late 124s-94/95s]
That site was great and free , but they finally dropped the free bit..
The later improvements , I believe, were the type of seal on the piston itself,[ teflon replacement, I think], whereas the early ones actually had piston breakage/failure.
both with the same result...except the later ones would stick, causing an intermittant problem, whereas , the old ones just broke into pieces and you called a tow truck...
Tranny guys here prolly know exactly.......