I have a 1979 Monte Carlo, 2 door with a lot of frame rot in back end. I also have a 1980 Oldsmobile cutlass, 2 door, with that the body and motor is junk, frame is solid though. I beleive the frames are the same, but not sure. Can I take the olds frame and put it on the monte carlo body.  

To sunshineclean.  The frames are the same. the amount of work involves a considerable amount of labor. Also,frame/chassis mount bushings may require replacing as time deteriorates and dry rots rubber. I currently own 79 Monte-Carlo with t-tops. I have owned 78 pontiac lemans,grand prix,80 m/carlo,and 80 cutlass. All your suspension,and frame parts are interchangeable. You will have time involved adjusting fender,door,and hood to nose spacings.  

I was going to order a urethane body mount kit, as far as the labor goes it seems like its a trade off of trying to repair the rotted frame or just do the swap. Just wanted to make sure that everything would bolt up. Thanks for responding back.  

i would think the body and motor would come off the cutlass first...    then while it still rolls around on the suspension.  take it to a sand blaster...  have it cleaned..  then get it back and use a  coating on it.. like a bed liner coating.. it does come in gallons.. and quarts .. rolled on and brushed on..   it wills stop any farther rot...    be sure that you don's loose the pink slip on the cutlass... as there are vin numbers on it.. and some states check them...

since you seem to live in a rust belt area... you might want to invest in spraying the body bolts with multiple applications of wd40 before trying to loosen the body bolts..  

it does not matter on the cutlass but on the monte carlo.. you dont want to have to drill the broken off bolts out of the welded in nuts.  

I actually prepping the monte, just because of where it is at, I was going to pull that body off and put it on a dolly and the back of the garage. Then bring the cutlass in tear it down, remove the enging, tranny and start removing everything else. Where I live at I have a place that would blast and powder coat the frame for 350.00. With everything set in front of the monte body I can reassamble the frame, pick up the body and just slide it under. Probably a little time away from that. I have started spraying the body mount bolts, etc on the cutlass with pb spray, and will do until the weekend when I am ready to take it apart. Any suggestions on whose body mounts to purchase.  

They're both G-body chassis cars, the body mount locations should be exactly the same between the two cars, get some new body bushings and swap the frames out.

While you've got the body off the good frame, wouldn't be a bad idea to clean it up and use some Por-15 to seal up the frame from corrosion.