Just had my 700r rebuilt about 800 miles ago. I mostly drive in drive and hardly ever in OD. The other day I put the truck in OD to get on the freeway and the truck started surging around 45-60 miles an hour. Mostly when giving the truck gas. I switched it back to Drive and was back to normal... no surging. Truck runs fine other wise and didn't have this problem until I had the trans rebuilt. Any ideas on what may be going on? Thanks.