I've got an 8ba in my '39. I was running flex hoses with a reducer to adapt down from the 1 3/4 inch '39 upper radiator top inlet to the 1 1/4 inch thermostat housing inlet on the 8ba. I think I still have the part number in the shop and maybe the hoses since I changed over to 1 3/4 inch thermostat housings that I got from Model Engineering (cheaper than Drakes and they had them when Drake was on back order) which allows me to run flex 1 3/4 inch flex hoses on both ends. I'll check for numbers next time I'm in the shop.