Legality of swap...
 

Back in the 90s I had been told that it was illegal to put an older engine in a newer truck. For example, If I wanted to put a 12v in my 1999 24v, it would be illegal because the engine had to be the same age or newer than the frame. Then I read about glider kits putting older engines in newer model year trucks. So what am I missing? Are they using old frames???

To the best of my recollection...there is no law restricting engine swaps, but the smog requirements follow the year of the engine, not the vehicle. So if you install a 2006 engine in a 1986 car then you have to follow 2006 emissions. I could be wrong as the laws may have changed so a call to the California Bureau of Automotive Repair and see what they say.

I am in Missouri. I guess I am crazy because I thought that the emissions requirements were tied to the frame age, which would stop people from putting older engines in newer frames. I guess I got this from someone who I either misunderstood or didn't know what they were talking about. :)

I missed the part where you're in Missouri... Is there a Bureau of Automotive Repair for your state? Someone to check the emissions laws with?

My understanding is you can not put an older engine in a new rig. The emissions need to match the engine that would have been in the truck for that year.
Getting a 12V to put out emissions of a 24V, sounds unlikely, therefore I would guess that swap would be a no, no.

I usually hear about people putting newer engines into older trucks.
The '95 12V motor I am putting in my '78 Ramcharger is an example.

I would check with your local laws before doing a swap like this.

This is the EPA's opinion on federal law concerning engine swaps of this nature...:2cents:...Ben

Clear as mud...as expected. I say call your local smog shops and see what they have to say.

I was toying with the idea of buying a new RAM and putting an old 24v 5.9 in it. Similar to the glider kits being sold.

Don't assume the Bureau of Automotive Repairs in your state will follow the actual laws. Been there, done that, got the tee shirt in California. Talk to the people that write the laws, not the ones that enforce them.