Any idea what this is?
 

First project truck, going pretty well, but i can't for the life of me figure out what this is.... There truck is a 1964 GMC 1000 but has a 261 in it, three on the tree...
https://i.imgur.com/TMwlmtC.jpg

Re: Any idea what this is?
 

Chrs:
Have you climbed underneath to see what it is attached to?

My guess is that the motor that was installed had a starter that used a foot pedal. Foot pedal levered the starter drive into flywheel and engaged battery voltage simultaneously. Was popular in cars and trucks in early 1950's.

Hope that helps.
Regards
Steve
New Orleans

Re: Any idea what this is?
 

Steve is probably right. Looks like the starter pedal my old '41 Chevy had. I'm guessing a previous owner hacked a hole in the floor to fit an older engine in your truck.

Re: Any idea what this is?
 

stomp starter for sure.
You probably have the only 64 GMC with a 261 engine in it. This is a Chevrolet truck engine that was produced from 1954 to 1962 and usually put in heavy big trucks
This one is in my 1953 3100

Re: Any idea what this is?
 

Definitely a starter pedal for a much earlier truck engine. Both Chevrolet and GMC used pedal actuated starters in the early 50's, although each used their own engines. Yours has a transplanted Chevy engine.