I looked it up for you in my Chevy parts book that covers 1946 -1972 C10,20,30 dated 1977. I've often times found these books to be confusing in their listings, but the best I can decifer is as follows.
60-63 all, part# 1991784*, 84" overall length
64-66 Ser 10-30, part# 1991808*, 65" overall length
(*universal length, cut to required length)
They didn't specify any difference in engine size in the listings.
I'm assuming they're so long so they would fit the vans as well???? These part numbers came with the knob, wire and tube. In addition to the length being different the knobs could have been different as well, mabey one had a chrome knob mabey one was black???? I know this probably doesn't answer your question, but it may give you some insight on what to look for.
