Could it be because Blind Pew is a character from the books while Spa'am is not? I mean I don't really no much about public domain and copy right laws and what not but I wonder if that could be the reason.
I couldn't find a picture of the Ford Woody used in the Muppet Movie but I have pictures of
Gonzo's plumbing truck front view
Studebaker (Electric Mayhem style)
Studebaker (Normal style)
Electric Mayhem Bus
just check out the front page of Muppetspicsandthings.wetpaint.com:D
that's cool my friends birthday is March 14 wait a minute that's probably why he chose Einstein for his biography book report (I chose Jim Henson and finished the book in 2 days he had an interesting life)