'60 Dart clutch question...

Hey guys:

This is for sure an "early" question but don't know if a '60 counts as an A, think it probably doesn't but you guys know a lot, so here goes:

One of my youtube subscriptions is replacing the clutch in a 1960 Dart Seneca, slant 6, three speed.

They ordered a clutch, supposed to be base model, whatver that is. Got it, but the new clutch is at least an inch larger than the old, and the throwout bearing is about 2 inches shorter(the old one appears to have a housing about 3 inches long.

Can anyone tell me what clutch they need to order? I'm sure they'll appreciate it and I'll direct them to the site in the future.

Thanks..