New lenses went on my '88 almost a year ago. The job took about an hour total and I let the sealant dry overnight before re-installation. Lenses cost about $53.00 (if I remember correctly) and the job was easy. I've always lived in southern US so there isn't the corrosion to deal with that others have - all in all I'd recommend new lenses if you can get the assembly out easily. The old plastic lenses come right off using a small putty knife as a pry tool. Then you remove all of the old sealant from the groove in the assembly so that the new lens bead snugs right down in the groove. Once you are sure of a good nesting remove the new test fitted lens and apply sealant inside the assembly groove and push the new lens into place. I used some small spring clamps to hold the new lenses tight while drying.

Note: I was careful not to touch, clean, or otherwise upset the reflective inside of the light assembly as everyone advises this stuff is very fragile. Job came out just fine.