I believe the support rods were for the NP203. I don't know if they bolted up to the NP205. I also don't know if they put the TH400 in trucks with the support rods, but I blieve the bolted in where the transmission case bolts to the engine block.
You might want to ask over on
CK5.com or
Pirate4x4.com.
I got an aluminum flywheel/torque converter cover from a
4x4 shop/junk yard in my area along with a "K" case for my '69. My neighbor gave me one of the support rods, but I never installed it.
I did a google image search for "flywheel cover" and these two came up (hope they work):
