[rotorwrench]

With the old transmissions you sort of have to take what ever is available. I've heard of folks having stack up problems with clutch plates due to different thickness. This can lead to confusion so it's important to order from some outfit that can back up what they sell. O-rings are another thing. Some of the Borg Warner designs have some flat or square/rectangular cross section o-rings and some sources sell the round cross section types.

There are a few guys that specialize in the later Thunderbird transmissions and they should know of any substitute parts from later transmissions that can be used in older units. It pays to reach out to these folks sometimes just to find out if there are any tricks to the trade.