What do you drive?
Ritchey mountain bike is what I drive most often, but I have a rusty '83 Econoline "*******' wagon" for when I'm feeling lazy. Actively working on a 1957 Ford panel truck. Not currently driving: a 1960 Ford panel truck, 1959 Merc stepside, and a 1960 Merc styleside.
Econoline has a 300 six and auto; all but the '57 panel have 223 sixes and 3-on-the-tree. The '57 panel has mounts for a small-block as well as the 223, but unless a nice SBF falls into my lap it'll get a 223 and a 4-speed. Merc's have Dana 44 rear ends; Fords have 9".