Hello all. I am in the process of rebuilding my 454 and noticed when installing the oil pump the drive for the pump is about a quarter of an inch longer then the old pump drive. The part number for the pump is M-77. I did a search on the Melling website and they list both the M-77 and a M-77G for the 454 Chev. The M-77 is for a car application and the M-77G is for a pickup. If I have the wrong pump I don't think I'll be able to exchange it because I tacked the pickup tube in plave before I realized the difference in the drive length. Has anybody ran into this before, and will the distributor still fit with the longer drive? Thanks Jerry

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Almost all of the big block pumps are interchangable. I bet the drive is not really longer, just the body of the pump is cast a little different. The M77G is the same as a M77 except there is a gasket between the cover and the body, mandated by GM. Put both pumps on the block and measure where the drive ends up and I bet they are the same.

The new pump I have is a Melling pump, Part number M-77. I set the two pumps side by side and the new pump (M-77) is about 1/4'' longer from the surface that mates to the main bearing cap to the end of the pump drive. I guess what I could do is to set the intake manifold in place, I don't have the cylinder heads back yet, and see if it fits. I guess I was wondering also if the new oil pump was mis packaged at the factory. Thanks Jerry

is there a different shorter pump drive shaft available? maybe a small block one? or are they the same as big blocks?

Well Bill you win the bet. Sure enough the pumps are cast differently and the height of the drive is the same. Thanks for the reply. I feel like an idiot, but at least have piece of mind. Thanks again, Jerry.