What to look for on an Oliver 1800

I have the option of trading my JD 1020 with a loader for an Oliver 1800. I had the serial number but can't locate it. I believe it's an "A" series. It is a diesel. I've been thinking of up sizing so I'm a bit interested in this tractor. I have no previous experience with Oliver and was wondering if there were any key items to check before I consider trading. Over all the tractor is in good shape. The metal is straight and complete. It starts and runs nice. I've seen the tractor operate. The owner has baled hay with it on my property using a large round baler for the last 5 or 6 years. So this isn't a completely unknown entity. I have the option to use the tractor for a few days to try it out. Parts availability seems pretty good but are there items that are tricky to locate that I should check before taking action? I may borrow it for a few days. Then I'll post pictures and get the serial number. I'm no stranger to dealing with odd tractors. I've lived with a MM 335 for about 30 years now. But the 335 is getting a little tricky to find stuff for. I'd rather not have two tractors like that.
I'd also like opinions on value of the 1020 to the 1800. I bought the 1020 as a basket case and have gone through the motor, the reverser, clutch, radiator and a few other items. The only real draw back it has is the rear tires are a bit worn. Maybe 10 to 20 % left. It runs and operates nicely. I don't follow the tractor market close enough to know values very well.
So any insight as to what to check would be greatly appreciated. I'd like to thank anyone who replies ahead of time.
Thanks and best regards to everyone.
Howard
Dundee, NY

Be advised, the 2speed freewheels in low side. Make sure the brakes don't lockup when traveling forward. Make sure the hydraulics lift smoothly, they are a bear to replace hyd pump. I hated the whole hydraulic system on mine. I could never hook up anything without getting hyd oil all over me. Who ever designed the system should have taken a look at another tractor brand, they could have made it a whole less complicated. I had to put fluid in the rear tires to pull a 4x14 ihc plow, had new tires on it.

We have an 1800 C diesel and I love it. Nice to drive, super easy on fuel, pulls like an ox. We added connect under pressure couplers to make hooking implements up easier. The biggest down side to the 1800 series in general is that they had a bad gear angle/heat treat issue on the bull pinions and they were prone to splintering. We didnt find this out till after we had bought ours and we had to put new bull pinions and bull gears in it. Unfortunately the only way to tell if they are shot is to pull the hydraulic unit and physically look at them because on ours the teeth on the gears had better that 1/4 of the material chipped off of them and the rear end was still quiet as a church mouse. Other than that just look for your typical stuff, hydra shift works in direct and hydra-power drive, holds good oil pressure when warm, starts back up when warm (if it starts hard after it warms up thats a pretty good indicator that the injection pump is getting weak), does it blue smoke and if it does, does the smoke go away after the engine warms up. Stuff like that. Parts are easy to come by since AGCO still carries most of it new. As for value, we gave $4000 for ours a year ago and it is a nice straight original that has been in our town its whole life.

I sent you an e-mail, did you receive it? Big differences between the A & C series those 2 are talking about.

Yes. I'm sorry I haven't had a chance to reply. I'm on my pad I'll email shortly. Howard

A lot depending on the loader and the condition of each tractor and their tires. If the tractors are in similar condition, I'd guess you could sell your 1020 and loader yourself, then buy the 1800 for cash and still have $2,000 left in your pocket.