I wonder how do you solve the problem of oil pump for gen1 car. It is not available anywhere. Only 93+ is available and they are not interchangeable.
You can try and see if its possible to get one on a special order from japan. Im waiting on a few discontinued items to arrive that I bought through mitsubishi and then they basically ordered it from japan. If I were you id contact your local mitsubishi and see if thats possible.
I always rebuild them rather than replace. I think the rebuild kit is still available.
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Hello Jtanabodee, just curious to know do you still have the gen 1 oil pump?
Is the rebuild kit sold from Mitsubishi??
Hello everyone, just wanted to share this information on the First Gen oil pump restoration/rebuild/cleaning: First of all, I am sure Joe has done this several times and knows the procedure for a complete restoration and rebuild and knows what to look for as far as wear and tare is concerned, however, I dont believe there has been much discussion on this on various GTO forums or on Joe’s website, if there is? then I may have overlooked. Now taking into consideration, that the First Gen GTO oil pump is obsolete!!
or is there one that has been manufactured to meet or exceed OEM specs, so with that being said, there is much pain and suffering for the First Gen GTO owners. I am not 100% sure if there are any variations between the oil pump design for the First Gen GTO in regard to trim ( Base, SL, TT ) but I did discover this issue a few years ago about not finding an OEM manufacturer that makes the oil pump for the First Gen TT. I was looking to buy a new oil pump for no apparent reason,( not that I had issues with oil pressure, just wanted new parts!! 
but after I realized the truth, I then decided to disassemble the old one and check all parts such as the gears and relief valve, so this is what I did and hope this information shall be helpful to others.The oil pump assembly was removed and cleaned up, then I took the housing apart, NOTE: be careful not to strip the heads on the 7 screws holding the back plate. They were a pain to get loose and I did strip two. Once the back plate is removed you will see the gears. I then removed the relief valve checked it thoroughly including spring tension and then everything was vapor honed and put back to together with a new seal from KOYO, new housing gasket, also new screws for the back plate, but I did not change the gears since I did not know what to look for as far as wear and tare is concerned ( definitely there was no rattling noise when I took the pump of the block and shock it
) if there had been a noise, then rest assured, the gears would have been broken or completely worn) and they looked great including the crank shaft, no scuffs of any sort. So I did something a bit different, after doing some research, I abrasive blasted the gears and coated them with an anti-friction heat resistant material, the same stuff that is used on piston skirts and high friction areas, so if you are wondering why the gears look black? 
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A nice explanation- however the picture you show is of a second gen oil pump as you can see the bolt holes for the crankshaft position sensor. The 1st gen ones don’t have this as it used a CAS on the heads. Or am I missing something…
Hello 3KGT, no you are 100% right, I just uploaded the wrong pics, this one was for one of the GTO forum members that liked what i did to my old pump and wanted his done the same way with coated gears. I have to see if I took any pics of mine but it should look the same, regardless. Speaking about how one can tell the big difference 
is not via bolt hole location but the complete lower design where the oil pan bolts on. The 93 and up oil pump has a much wider curvature angle to compensate for the 4 bolt block design. The area I am referring to is here right behind the crank pulley.
Thanks for the information I have found the work around. If your housing is still good, just the billets inside are the problem. Just change the billets. Rvengeperformance has it but the price is a little over 500$. I cannot afford that price since I am oversea and the dollars are so strong at this time. So, I order the 2nd gen oil pump for Melling and took out the billets to use with the old housing. The size is exactly match. My mechanic is going to test it today. Hope it works.
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Hello, I was previously going to buy a set of Billet gears, but was told by others that there was absolutely no point to spend so much money on billet gears on a stock build or even boosted engines. Manufacturers do not make OEM oil pumps with billet gears unless it is specified in the product listing. So if you are going to pick up an oil pump from Melling rest assured the gears are not made of forged aluminium or forged anything ( Billet ), these gears are powdered steel. And yes you can buy any oil pump for any years and just use the gears, I dont believe Mitsubishi changed any internals designs of the oil pump, but I do not know for sure since I have not owned a second or third generation GTO to take them apart and discover design changes.
Thanks for bring up this topic and goodluck 
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It’s not even an original factory pump
I would like to update. It works perfectly. Oil pump can generate the pressure more than enough for the engine. Not too bad for Chinese oil pump but I will keep eyes on the oil pressure from time to time.
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