[benoit454]

OK I'm lost, I know you are taking the motor from one and putting it in another truck.

What did the truck you are putting the motor in have in it before? Was it or are they both gas motors?

The exhaust looks like every other manifold setup I've ever seen, only difference maybe in the manifolds, but I'm not sure. if so then the engine you pulled from the truck if it's manifolds won't fit the one it's going into, then what happen to the manfiolds from the truck the motor is going in?

Oil tube? you mean the sending unit? Did the truck the motor is going in have a motor? If so it be alot easier because you could try the original stuff and try the stuff from the new motor going in it.

gmc manifolds and chevy are the same, only difference would be if you had a buick, pontiac, or olds 350 in the other truck.

Speedo cable? You mean the throttle cable that hooks to the carb? if so then maybe the truck had a straight 6. Ours was like that, going from a 76 straight 6 truck with a 300 series 6 cylinder to a 350 v8 it was way too long. if it's a speedo cable that goes to the transmission and works the speedo in dash I have no idea why it be longer?

There are 2 locations for oil sending units, ones above the filter, and the other behind the intake, some have big bulbs back there or just a sending unit the tube hooks to. I'd just buy an aftermarket guage for about $10-20 and it comes with line, fittings guage and all. Then just mount it under the dash or wherever. I've had them under the dash and also made a plate and removed the vent above the heater controls and put in 2 guages there.

Yes they are called one piece window kits.
There's a thing here about group purchase for them, and captkaos had a link on his site for them also.