'88 300 TE questions

[rjk]

My R&R of the flex connectors (driveshaft) went smoothly but there is an anomoly. The website called for different front & rear connectors which came as listed. The front(?) one looked heavier and had thick, odd looking washers while the rear(?) had round, thinner washers. When I dropped the old ones out, they were both the same right down to the molded-in numbers . Did a previous mechanic take a shorter/easier/cheaper way out? Is this why my rear connector was shredded? Which connector is correct for the tranny and which for the diff.? I currently have the heavier conn. on the front/tranny union and the smaller on the rear/diff.

I'm looking at a rear main seal replacement, how big a bear is dropping this tranny? Straight forward, or should I be aware of any "special" items?