Im getting ready to do my trans this week. Ill pass along the info I gathered.
I was also looking into the kit from SunCoast but was finding they don't hold up, even though they have an awesome rep in the Dodge world not so much with the E40D/4R100.
So then I was looking into RacerX. I was finding most people were having good luck with their products but was finding they've had an iffy customer service with their products in the past but most were having great luck from them. I ended up purchasing a billet shaft and a few gaskets from them. Only issue I had was they couldn't ship to a different address than the billing address (college...lol) Not a biggie.
I ended up ordering an ATS kit through Alligator, even though ATS has a past Ive heard their getting much better and Im believing this, I ordered the kit and it was shipped direct from ATS and was here in less than a week. Hoping this holds up.
As far as the trans go Im going with the ATS kit, Valair TC (supposedly made by DPC), RacerX billet input shaft, and Transgo Tugger shift kit. Since Im doing this myself its emptying my pocket around 1800.