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| | | Forums66 Topics128,087 Posts1,055,982 Members48,430 | | Most Online14,466 Apr 26th, 2026 | | AD Chevy Trucks Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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For helping keep this great
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on the Internet for over 30 years! and not clogged down with Ads! Again, thanks! | | | | Joined: Dec 2003 Posts: 2,733 Shop Shark | | Shop Shark Joined: Dec 2003 Posts: 2,733 | Grumpy, it sounds like you have a direct mount pump. These are either a 9 tooth SAE "A" flange (2 bolt) or a 13 tooth SAE "B" flange, 4 bolt as I recall. If the pump is a small displacement of say no more than 5-8 GPM then it is likely a 9 tooth A flange. There is no key holding the pump shaft to the female PTO shaft, only the pump mounting bolts hold them together. What you are referring to as a key is probably one of the teeth on the pump shaft. I say this because, as you point out there is no way to get at it and since the Allison PTO mounts above C/L and against the frame it is very difficult to get a good look at it. I'd suggest you remove the PTO/pump as a unit and once it is on the bench you should be able to get them apart. Be carefull not to crack the PTO case as these are S-P-E-N-D-Y. You don't even want to know what a replacement Allison PTO costs. | | |
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