[Farmall] Oil pressure problem / which is a keeper?

[br549 at hemc.net]

I have a 340U that looks great, runs well and burns no oil and does 
not smoke but has a oil pressure problem. It is fine (mid-range on the 
gauge) for the first half hour of running, then it drops WAY down - 
lowest mark on the gauge. I have replaced the gauge and oil filter so 
I'm pretty sure that the problem is elsewhere. Do you think it is the 
pump? What should I do next to troubleshoot?


My other dilemma is that the tractor mentioned above is a '61, has 
brand new rubber, new paint, straight tin, 3 pt. industrial hitch (that is 
missing the stabilizers and one of the stabilizer mounts), a 12 volt 
conversion (haphazardly done) and a PTO engagement problem. I 
recently purchased a '59 340U with power steering, remote hydraulics, 
fast hitch with 3 pt. adapter, working torque amplifier, delux seat, 
power adjust wheels, rear wheel weights, a horn but the hood, grille, 
front side panels are bent and all emblems are missing and the tires 
are shot. The '59 runs well (good oil pressure too) but smokes (think it 
is running rich - black smoke). 

To distill it down, one tractor looks really rough and has bad tires but 
has many options ('59) and the other looks great but has the oil 
pressure and PTO problems ('61). I will be keeping only one of them 
and I like the TA and power steering because I bush hog in tight and 
hilly terrain. Do I swap parts and make the "61 what I want or do I buy 
a parts tractor (know of several Farmall 340 tractors nearby) and start 
fixing the damage on the '59?

If you'd like pictures of them, I'll take some today and be glad to send 
them your way.

Thanks and have a great holiday weekend.