I am getting ready to start on my new project vehicle, a 1975 Crew Cab F-250. It has a 390 in it currently but it is definitely in need of a rebuild. It will be my daily driver from now on and will be operating at highway speeds for at least 25 miles a day, 5 days a week. I had an idea to put in a 300 L-6 for fuel economy. My question is will the 300 be working so hard to keep that Crew Cab moving at 80 mph that it won't be as efficient as, say, a 351? I can massage the engine for more horsepower but remember, fuel economy is a major factor. At the same time, I don't want a guttless wonder of a pickup. If the 300 is not the way to go then what engines would you recommend?

I was also thinking about using an AOD from an 80's pickup. How would that conversion go? I have the original 75 steering column available but I also have a 78 2wd steering column out of an F150 available to me (along with most of the rest of the truck, sans engine). The shift linkage is my main concern. I have already looked at those gear vendors overdrives but they are way too spendy. I have the time available to do a conversion but what aspects need to be looked at?

Also, I have noticed that bedsides or other parts for shortbeds are nearly impossible to find. Is there any way to stretch the frame or somehow mount a longbed? I think the LWB looks better anyway. If not, do you know of any place to find shortbed panels? Again, what aspects need to be considered to do a longbed conversion? Any help will be greatly appreciated!

 

I'm in the same boat. I have converted my 300/6 with an edelbrock 600, clifford intake, EFI dual exhaust, waiting on the install of the 270° cam. I have 410 gears in my Dana 60 and it cruses fine at 65 and maintains 17-18mpg. I'm hoping to get comprable hp with the instalation of the cam (to a small block V8 that is) We will see- The torque is there though. I also have an AOD from my old '89 mustang that I plan on installing this summer. Just make sure you build it up a bit to handle the weight of these trucks ie.. A+ servo - 2" O.D. band - bigger clutch pack - shift kit. You will have to build a bracket to mount the TV cable to the carb/TB for the trans. Low TV preassure will ruin the transmission in just a few miles. Proper install of this cable is the most critial aspect of the swap. I believe the 300/6 is internally balanced, so I think you have to knock the weight off of the flexplate. Not sure, help me out guys? Mine is a 72' highboy shortbox and I just love the looks- There are so many new crew cab long boxes on the market today, it's refreshing to see the shortbox-Just my opinion. I would love to get some pics of your truck if you have some- These are so rare, I am definatly keeping it for a long, long time