At the risk of feeding the fire, I will jump in here.
The first production run for the Oliver 88 was in 1947.  I know this is not consistent with the dates in the Morrell book but errors do have a way of getting into print. I do not know exactly when the early test tractors were built.  There are pictures of  prototypes of what were to become the 66/77/88 tractors that probably were built in the mid 1940s.  Interesting enough, these pictures identify the protypes as 60/70/80 tractors. 
As an Oliver dealer, we sold one of the first 352 88 Row Crops in l947. All of the 88s we sold in 1948 and later were the fleetline design. 
Side note: My dad and I attended the Oliver 100th birthday celebration in 1948 at the Battle Creek plant. They had a 77 Standard on display which I believe was the first Fleetline to be produced.