I just got a set of pistons with a set of rods I wanted and I'm trying to figure out what the pistons are. All they have is on inside say DRP 50. And has this number to 28235. Any ideas ??

Pictures ? measure the pin height ?

If they are flat top with no valve reliefs they are more than likely a smog motor replacement .

No there not smog replacement pistons there on aluminum rods I wanted I tink there diamond racing pistons Looks like the measure the same as my .60 over dome pistons I have already I emailed diamond racing the numbers and stuff to see if the can tell me what they are for sure

is that 28235 engraved in the top of the piston ? Pictures ?? do they have valve reliefs , your poor description is obviously not getting you any answers.

pistons are already hung on the rods correct? Set a piston top down on your kitchen table & set a round (say 1/4") rod horizontle in thru the pin on the top (now the bottom (floor) since it is inverted) & with the rod extended out measure from the table up to it (dimention A). subtract the rod (ie 1/4") thickness from that to get dimention B then subtract .150" (wall thickness) from dimention B to get C then add in .5045" (1/2 of pin OD) to C to get the compression height.