Is this a stock or aftermarket fuel cell?

[BigCarl]

Its in a 1972 Blazer CST, PO had dropped in a 454 with a Quadrajet, but instead of a manual pump, there is an electric pump.

I am wondering if this is a factory fuel cell/tank or an aftermarket one. If so, is it larger than the stock 21 gallon or the same size?

Will a stock fuel sender fit into this, or do I have to use something else?

I am planning on converting back to a manual pump.

From rear
[IMG][/IMG]

Driver's side
[IMG][/IMG]

Passenger's Side
[IMG][/IMG]