I'm in search of two different D4 starting engine fuel tanks. One is for a 5T that has the rectangular style and sits on the throttle handle perch . The other is for a 7U that's kidney shaped and sits over the pony carburetor. The 5T's was missing when I got it and the 7U that I started working on today is rusted through and looks like Swiss cheese.

Scott Flint in Hollister California makes gas tanks for Cat pony motors, and other sheet metal parts, call him on 831 636 8986

I have given up on steel tanks and rust flakes getting I my carburetor. The filter bowl is no longer available. I have ordered a plastic tank and flexible lines and inline filter and shutoff valve. I know it is not original but I will save all the old parts. I just want my D4 to start dependably and not have to worry about the carb.

I agree 8C361, though I'm fairly certain the tanks Scott Flint makes are made from stainless steel, so no rusting issues, just need to deal with rubbish modern gas that has the shelf life of a dead fish in the sun......

I visited Scott back around 2019 and he showed me one of his new pony gas tanks, it looked pretty good to me, and no, I'm not getting a free donut and a cup of Joe to say something good about him, he makes great parts.

I appreciate the feedback and information and figure I'll just make my own, after all I am a retired sheet metal worker lol, just thought I'd ask because I like original parts.
I too have gotten tired of cleaning carburetors time after time but try to keep everything as original as possible even though my machines are far from show pieces. My solution to that problem has been to remove the copper fuel line or cut it and install not one but two inline filters. Haven't had any issues yet.

You could also insert a 1" stem at the inlet of the valve/bottom of tank, so any sediment/water settles at bottom, and not drawn into fuel line. Inexpensive "fix". JM

I was talking to Scott Flint a few days ago, he is fighting throat cancer at the moment, and has just come out the other side of a very brutal treatment process of radiation and chemo, he will be having tests in June to see how successful those treatments were, and I for one, hope he has it licked.

He was telling me the thread on those pony gas tanks is a oddball military thread, something similar to a water canteen size, I'm not sure why Cat would have chosen that thread, perhaps it had to do with a outside supplier producing the caps? Anyway, if you make a new tank yourself, just be aware the filler neck thread might be a oddball, if you were planning on using your old cap.
Mike