has anyone gotten one of those wiring diagrams that are in color they are selling on ebay? looks like a good idea as looking at all black lines on paper can get confusing. if you got one, did you like it? one other question, would there be a big difference between a 74 & 75 wiring as the 75 gm manual is only a supplement to th 74? thanks for any help.

I just bought a diagram for my 81  from Don Olson (vetsvette2002@yahoo.com) and it's great.  Paid $37 and it's worth every penny...

There is some minor differences in the wiring from '74-'75. '75 was the first year for the HEI ignition system so the wiring for that is different.
The seatbelt warning/starter interlock systems('74) were different, also, except for the very early '75s.
There are other things too, but if the "supplement" doesn't specify a particular change in a system wiring, then it will be the same as the '74.

[QUOTE=NuclearBob]I just bought a diagram for my 81  from Don Olson (vetsvette2002@yahoo.com) and it's great.  Paid $37 and it's worth every penny...[/QUOTE]

is this the only way to contact him is by email or does he have a web site.

I have only used email.  The number on his business card is (630) 947-3284..  Hope this helps!

I broke down and bought the original Helm's shop manual for my '78 and it came with a beautiful color nicely detailed wiring diagram. Most useful part of the kit. Mine was about $100.00, but I checked www.helminc.com for the '75 and it was only $75.00. At any rate I found it a super investment.

Dave