Now you are going to make me think. I started with an Oliver dealer when the 1800 was introduced. We sold one that I had to put the coversion package in. That was 45 years ago this summer. I need to do some research now as the 1800's start at 90XXX and this change affected tractors with tractors up to either a 92 or 94 something serial number. I get to be a 4H judge  the first two days  and I need to read up on some of those projects so it may be wednesday when I get back to you, John