That's a typical break pattern for cast iron.

It seems like aluminum but .....

Does look like aluminum, cheap aftermarket???, homemade??? I dont believe Cat would make something like that! Check it with a magnet or hacksaw. Look at the wear ring where the pins are, cast steel wouldn't do that so easy.

Magnet will not stick to it. Only around the valves 

I have 1 used piston and I removed the 8 rings seals and have some new one in stock

I sent you a pm, thanks

Hi Team,
have resealed many of these early blade lift cylinders over the years from different sized machines and indeed the pistons of that era were aluminium from the factory.
These units were amongst Cat's first entry into the hydraulic system field--they worked well and certainly did not score bores when they rubbed them.
Cheers,
Eddie B.

Thanks Eddie. Learn something new every day. I guess the pressure would have been much lower then as well and the valves in the piston would help stop end of travel spikes. Could it have been part of the seals that caused the breakage if it lodged between the piston and the head of the cylinder?

aluminium alloy would be okay as these old girls ran at max 1500 psi normal w.p 1200 psi.
if you got a block of high grade ally any good machine shop should be able to make one on the milling machine.

if you could give them a cad drawing that would be even better.

as a sidenote make sure the thread on the shaft and nut are in good order. a neighbour had to replace a ram on his track loader as it pulled the threads and the shaft blew out of the cyl he said it made a hell of a bang. he was able to get a reco unit but it was a couple of grand to get one.

Here is the new to me piston, is there a dirrerent style of valves? Mine has a spring the replacement one does not. The valve bores are a different size so exchanging the valves from mine to the replacement would not work either. My plan is to put it together and try it .