Cat D7E Oil Types

I have a D7E 48A with a fairly worn under carriage,sprockets are quite sharp. What is the best source of aftermarket replacement parts for it? I'm also in the market for sprocket section sets that aren't as worn out as mine since mine will slip when reversing up a steep hill. Does anyone have a sprocket set for sale that's in decent shape? Is putting a better set of sprockets on a worn UC a bad idea or will it work for a little while?

I don't want to spend the 20k for a new UC when I won't be using it that much, though if it ever gives me too much hassle I might do it.

Price a set of the segments from after market such as Berco. But Cat might not break the bank for segments.

Is AMT equipment a good source? They have almost everything for the undercarriage in stock.