-the cummins will not bolt to your gasser 727.
-your front end will collapse under the weight of the motor
-your rear axle will not know what to do with the torque from the cummins
-you will most likely want to have a diesel truck dashboard/instrument cluster installed.
-you front brakes are different than what would be under a 2wd cummins powered truck
-you will need a different radiator, and will need and intercooler if your motor is a 90(?) or later

your best bet would probably be to find a good running cummins truck with a bad body, and swap your good body onto it. your d150 frame/suspension/drivetrain is not going to be compatible w/the cummins

 

Hey guys I appreciate it. My dad bought the truck brand new in 90 and I just got it about a year ago so it has sentimental value. I will probably just go with rebuilding the 318. Sounds like more trouble than its worth. If I do rebuild the 318 though I want to put a performance cam and a couple other little things in it, anybody have any suggestions on where to get a COMPLETE rebuild kit?

 

Summit Racing, they have complete rebuild kits, and also kits that come with a cam intake and carb

 

Hey man i appreciate it. I will let yall know how it turns out. Im gonna do the rebuild first of the year. What do you think about hooker headers with magnaflow true duals?

 

Sounds good, literally lol

 

good luck!

 

If you really want to go diesel use the Cummins 4bt. Basically the 6bt (from Dodge 2500/3500) with 2 less cylinders. Much lighter, your 1/2 ton can handle it. Many came with GM auto's. Can be found in older GM step vans, many on E-bay around 2k.
Thats my plan for when I get tired of (or blow-up) the 225!