starting issue

[Red Rocket]

i have a 1970 GMC pickup 4X4 and when its cold out or the truck hasn't been started for a bit it will fire up fine but if i drive it and the engine is hot and i try to start it i get nothing. the starter doesn't even click but i have full power. i have installed a new solenoid and still have the same issue. no idea what it could be i have been trying to trace the wire and the guy before me has done some home wiring which i think is most of the problem.

any suggestions??

thanks dan