I purchased my 51F1 with a 226 Flathead 6 in it 5 years ago. It had been sitting for around 15 years according to the PO, the Flathead was not siezed. The PO told me it was the orginal engine and it had only been rebuilt once back in the early 70's. The valves were all stuck open but I managed to get them freed up and it running, I was able to drive it 40 miles home. My driveway is sloped so I used the engine to move the truck in and out of the garage while working on it. The more it ran during that time the better it ran. I' am still running this incredable Flathead as a daily driver now, and have been for the last 4 years. I picked up a 53 Merc V8 to drop in when the 6 dies but it is still going strong and shows no sign of giving up anytime soon. I beginning to wonder if this engine will out live me. The only thing I have against the 6 is that some of the internal parts are getting real hard to find, Like the oil pump drive gear. The 7HA and OHA models both have a different gear one is 7 tooth and one is 8. I installed an S-10 5 speed and a 9" rearend with 3.23 gears a couple years ago. That S-10 trans is in my opinion perfect for that engine, I'am amazed everytime I drive it of how great it drives now.