Hello, pretty new here. I am in the process of assembling a 4d55 that I bought used from a guy, in pieces. Lots of joyful discoveries of missing parts, but it is coming along! Anyway, I don't seem the have the front lower case/oil pump assembly. I have found a few 4d56 oil pump assys on ebay for like 70 bucks or so, but I am not having any luck finding the 4d55 piece. My question is, are the 4d56 versions the same by some stroke of luck? Or compatible anyway? And if not, I suppose i would love to hear any ideas on where else to look!