[Woodz428]

I believe the mirror 105 is on all the later (post '71 or so) blocks instead of the 352. Also the T doesn't mean it's s heavy duty FT style block because the 360/390 bread and butter pick-ups have that type of casting # as well. Finally the 391 (forged) crank as well as all the FT cranks have a bigger snout (as well as some dimensions on the flange) that's incompatible with FE type dampeners. While it can be machined to use in an FE,that's not typical work done by rebuilders.It's my understanding that the later mirror blocks aren't as stout as the earlier ones that have the 352, I think it's because of newer style casting used (similar to the thinwall small blocks)