There strong that's for sure...........I've seen a few grenade behind a SBC. Was due to lack of cooling and overloaded towing. There weak spots are the input housings and roller clutch. Planetary sets are strong in those. I rebuilt quite a few of those I was a heavy line tech for GM. But behind a 305 I don't see any problems. My buddy had a 4L60E I built for him behind his 1st gen vortec.....mated with an Orion t case. He had clearance issues with the oil pan and front driveshaft. I think there is a company who builds an extended adapter for that issue. He had to run a Nissan style mini drive-shaft flange, but it wasn't very strong. He now has the adapter and will be installing it. I will try and find out who makes it.