There was talk about an aluminum XR block. In the post I found, Rick never
acutally "said" there would be one and never corrected anybody for expecting
one. I'm for certain he said there might be an aluminum version but, you can
only search back, so far now.

XR2 Block ***Preview Pics***Extra Pics now added

There were also solid aluminum SB Mopar blocks. I don't know how many were
made or who made them but, a friend of mine, got them from Fowler Engines in
Columbus, OH. Kent Ritter bought them(2) for a guy building a Jr. Fueler.