First Dozer Case 450 need insight

I'm looking to purchase my first dozer for light work around my 40 acres. Clearing some brush and small 6-12" stumps. Cutting in trials on uneven slopes. I found a Case 450 that has a freshly rebuilt engine with 50 hours on it. I'm not familiar with dozers so I would like to know what to check when I go take it for a test run. The seller is asking 6800 and I talked him down to 5500. He was unsure of the year and model of the dozer I'm guessing it's a 1970s Case 450. He bought it as part of a package deal from his neighbor and has no interest in it. Here are some pictures let me know what you guys think

I cut my teeth on dozers so to speak on the exact same machine back in the early 70's. This one looks like early 70's to me. They are a nice nimble little machine for doing lighter work in my opinion & easy to run. Check all fluid levels including the final drives. Much for leaks evident? Do you know how to check the undercarriage for wear? The price sounds reasonable if it is a good functioning machine. A 450 of that vintage was about 45 hp.

Went and took a look at it. Most of the bottom rollers needed to be replaced which is more work and money than I'm willing to put forth. Both of the front actuators for up/down were leaking pretty good. Fuel tank had lots of metal at the bottom. The dozer wouldnt really push dirt in anything other than low/low which I thought was odd but I am no expert. Most of the engine guages also did not work. I also couldn't find any serial numbers anywhere on the dozer they had all been removed at some point in its life. The seller started to get pushy and rush me into buying to towards the end dropped the price down to $5000 because of the issues I was finding. I decided to walk away... on to the next one