Can anyone tell me if a radiator out of a 77 L82 will work alright in my 77 L48?  I think these are inter changeable but I wanted to check with a few of you beforehand.  Thanks for the help!

Absotivly, posolutely, they will interchange. Should have no problems at all. The only possible issue might be with the rubber cushions...if the radiators are both the same thickness, they'll work fine. If the one you are installing is a bit wider, all you would need is the wider rubber cushions.
Make sure the "new" one has the trans cooler fittings on it, too.

Thank you very much, what do you actually mean by "making sure you have the trans cooler fittings on it".  Thanks for your help!

The automatic trans cars have a cooler built into the radiator. Not all radiators will have this, such as the manual trans equipped cars. If your rad is coming from an automatic car, you're good to go!
Check on the pass side tank of the rad for two fittings for the trans cooler lines to go into...you can look on your car to see what I'm talking aboot.
IF the radiator you're putting on does NOT have the cooler in it, all is not lost...you can install an auxiliary trans cooler in front of the A/C condenser, and actually cool the trans better.