This page will discuss the top motors used by Chevrolet, Oldsmobile, Pontiac and Buick in the mid to late 1960's through the early 1970's. These motors have a seven digit number stamped in the motor end cap. The first four numbers are always 5044. The most common models are 5044611 and 5044586. For the record, these motors are typically a pain in the neck. The standard Method 1 rebuild/repair cost for these motors is $125. Purchase Method 2 is available only on a case by case basis for these motors, assuming I have one in stock ready to go. If I have one ready to go and we decide Method 2 would be appropriate, the core fee is $100. I'm putting up photos of a few models these motors. They're all similiar, with the mounting style, mount locations and hose port locations being the only significant differences between model numbers.
I've seen several auctions on ebay that are advertising a Mustang/LeBaron top motor (Number 3 on the Ford page, Number 2 on the Mopar page) as a 1961, 62, 63, 64, 65, 66, 67, 68, 69 etc GM top motor. This is not true and they will not mount in a 5044xxx motor style convertible. These motors were not even made until 1988. The mounts have different center to center distances on both width and length. The hose ports are also oriented differently, which can cause the OEM hoses to kink. The electrical connectors do not match and would require the wires to be cut and spliced. Basically, you'd need to jerry rig the heck out of it to get it to work. I've emailed the sellers several times and have yet to get a response from them as to how these are supposed to be a direct replacement. That alone sets off all kinds of warning flags in my mind.
The top motor shown in the five photos below was from a 1963 Olsmobile Starfire.
The top motor shown in the five photos below was from a 1965 Chevelle.
I've seen the 5044586 model come with a few different reservoirs. Some assemblies use four mounting points and some use only three.
The top motor shown below is a 5044611 model from a 1969 Cadillac.
I happen to have an interchange list printed out for this model that lists it being used on 1966 - 1970 Buick, Cadillac, Chevrolet Pass, Oldsmobile and Pontiac full size vehicles. This is the only model that mounts with the pump body below the rubber mounts. The mounting position makes it appear upside down.