Flywheel/Torque Converter Compatible?

[hitechredneck]

I'm swapping a TH400 out of an '86 CUCV Diesel (6.2) into a 1990 K5 Blazer with a 5.7 (Gas). The problem is that the torque converter from the Diesel is a 6-lug design and the flywheel on the Blazer is only a 3-lug. Will I have to purchase a new converter to mate up to the 350's flywheel? I've look at the specs on earlier 350's mated to a TH400 and have found a few, but the only difference being is that the 1990 5.7 has the one piece rear seal.
What do I do now?
I known that the converter from the original 700R4 will not go onto the TH400, so that leaves either finding another converter (more $$$), or finding a flywheel that has 6-lug design that will bolt up to a newer 5.7. Is the 4L80E (newer TH400) the same as the '86 TH400? If so, does anyone make a flywheel for the newer 5.7 to bolt up to a 6-lug converter for the 4L80E? (Damn, all these different numbers are confusing as hell!)
Any and All info would be appreciated!!!

 

[4X4HIGH]

You will only have 3 bolts that line up but that's ok, most only have 3 bolts and the governor is different between gas and diesel so it must be changed as well.

 

[colbystephens]

everything i've read says that the torque converters are different between gas and diesel, so you gotta replace it anyway. also, the part you're looking for is the proper flexplate, as a flywheel is for a manual trans. if you go to a shop and order a flywheel, you'll pay tons of money and end up w/ the wrong part.