The shorter tailshaft and housing is MUCH stronger!! We often substituted the shorter TH350 in anything even remotely high performance when I worked for the big transmission shop in Nashville.
We did most of the hotrod and racing builds around here back then. The rear drum and planetary holds up much better in the short version, so we would have the local drive shaft builder install a new tube in the driveshaft for the customer.
Never use a minor caliber bullet on a major caliber adversary