coolant reservoir cap???????

[JD1973]

I just got a new coolant reservoir, and its the only replacement GM sell for the 1973 C/K10
How ever it comes without a cap,
This new tank is very different from my original one.
The original tank was few thru the bottom of the tank and had a very small cap on it.
The new one has a 2in diameter hole on the top for the cap and is supposed to be fed thru the cap.
It didn't come with a new cap.
I tried part number 340194 (cap) it about 1/8in too small.

does anyone here know what part number or off brand cap will fit the new coolant reservior?

 

[Ricko1966]

A little more info, like what part# reservoir you're talking about,maybe a pic.

 

[nvrenuf]

Screw or snap type cap?

 

[Keith Seymore]

Sounds like the difference to me between an "overflow tank" and a "surge tank".

Overflow = one way; coolant moves from the radiator to the tank as catch can, but is not drawn back in.

Surge = two way. coolant can move from the hot side into the tank, and then be drawn back in as the system cools.

K