I had Dean Barker ( former Oliver/White engineer that worked on transmissions) look at your pictures. He had this to say:
[quote:wwg19rjq]
&quot;I would guess that with normal loads, those gears will last between 2000 and 3000 hours.  By normal loads, this would be at speeds of at least 5 mph doing field work.  If you put a ripper or a big moldboard plow behind it and go 3 mph, it won't last much over 1000 hours.  We had one of our Phoenix  test tractors that looked about like yours, and it lasted another 3000 hours.  I'm assuming this is the rear differential in the pictures.  It will help if you carry at least 70% of the weight on the front end, static weight.  We always figured the rear differential had to be designed to carry 70% of the horsepower, because of the weight shift while pulling without any additional weight on the front end.&quot;
[/quote:wwg19rjq]

On the production numbers, I saw a sheet one time with Whites on it, but my memory just won't hold all those numbers. I do remember looking up the 4-225 since I have one, and it was somewhere around 200 units made. I would not be scared of owning one though, as they used the inboard planetary final drives and for the most part, the transmission was identical to the 2-155. Those transmissions are tough and there should be plenty of used parts around. I have been told the turbo charged 3208 had a different block with more webbing, and were therefore tougher. Mine definitely runs smoother than other 3208s I have run.

 I think the numbers for the 4-270 were lower yet, but I just can't remember for sure. They were a unique tractor and parts may be harder to come by for them.