Missing upper idler

[Straight350]

I have a what I was told a 1968-ish straight 350 w/gas engine and a 6 way blade. My first dozer ever and really like it for around the property. It’s missing the upper roller/idler on both sides. I didn’t notice it when buying it, so I just want to make it right. Does someone have a link to this part? I have already put a new choke cable, checked all fluids, gave everything a couple pumps of grease and pushed around a lot of dirt on the motocross track. I also put a new radiator cap (8lb) from tractor supply, but it spits out the overflow tube a little here and there even though the temp gauge seems to be working fine and running around 190. Once I figure out how to post pictures I will be doing that. Thanks in advance