3 speed column shift engine/trans swap into an automatic body

[kdenney]

I searched through a several posts to find something related to this, but couldn't find anything that matched quite right.

I have a ½ ton 2wd 76 gmc lwb with the 250 I6 and the 3-speed column shift trans.  The body is in terrible shape - needs a cab swap among many other things.  Well, I found a ½ ton 2wd 77 chevy lwb with no engine or trans for sale locally for a good deal.  I'm in the process of finding out what engine/trans combo was previously installed in it now, but I'm assuming it is at least an automatic.

I'm thinking I can just yank my engine, trans, steering column, and pedal assembly to install in the 77, but was wondering if there is anything else major that I need to worry about eg. cross members, driveshafts, etc?

Any thoughts?  Thanks in advance!

[kdenney]

Ok. I found out that the 77 had a 350 with a th350 long shaft.  My 76 has a split driveshaft that attaches to a cross member halfway back to the rear end.  Anyone see any issues with just using the driveshaft already on the 77, or do I need to remove the old one from the 76?

[zieg85]

Drive shaft from yours is needed.  The total length of the 2 piece is longer than the 1 piece for the long tail shaft.  The only concern I have is the wiring is different between the 2 years.  AMP gauge versus Volt gauge and the steering column plug may be different and somewhere along those years the intermediate shaft that couples the column to the box is different.  If it were me I would use everything off your truck and start with just the shell of the donor.

[kdenney]

Thanks for the input Zieg. Roger that. I'm trying to make a list of things to take off my old one. The guy I'm planning to buy the 77 from wants to swap trucks minus whatever I need out my old one. I don't want to miss something and have to ask to get it later.

Do you think the cross member for the transmission is the same, or will I need to take that from the old one as well?

[zieg85]

Trans cross members "should" be the same if they are same emission groups, both catalytic converter trucks or not.  Tell tail signs are "unleaded fuel only" on the gas gauge if it is original to the truck.

[kdenney]

Mine has the catalytic converter; I need to find out if the 77 does or not.  I did some more research and found that the gauges changed from amps to volts in 76, so they both have volt gauges.  Is there any other reason you suggest using the wiring harness from the old truck (other than the steering column)?

[zieg85]

no reason the change wiring if your 76 column plugs into the 77 wiring harness.  It is even fairly easy to pull the turn signal switch out of the 77 column and put it in yours if they are both non-tilt.