That motor looks just like a marine wiper motor, which come in different shaft lengths.

Have you considered looking on e-bay or a marine supply store?

Here's an e-bay example of what looks like the same motor.

http://cgi.ebay.com/ebaymotors/Wipe...itemZ130027209231QQrdZ1QQsspagenameZWDVW


'51 Chevy 1/2 ton w/'62 261, HEI, offy, fentons, dual carter/webbers, t-5 & 12 bolt posi