Um!...... yes the old cracked see thru acrylic roof. Most cracks I've seen come from the rear at about where the panel curves over (~ 100mm) from the side at the rear corners. If they are only small, you can drill a small hole at the end of the crack, glue (acrylic cement) crack, fill hole. Or take it to "someone" with plastic/acrylic expertise, they will drill and weld it up. Or throw it away, but with there replacement cost I'm sure you will have a heap of takers only too happy to take it off your hands.
Replacements in Oz are hard to come by, and expensive from the States, that applies to both Acrylic and Solid f/glass types.
BUT REMEMBER, they crack from age, stress and incorrect roof lock in alignment ------ so if you get a Second Hand acrylic, it will most likely be as old as your original, so I would suggest considering a brand new one. Also " roofs aint all roofs" that is to say, for an 87 you buy an 87 roof, you will be very lucky if it goes on, you will need to release all 4 body locks and the 4 roof mount locks and go thu the setup precedure, ENSUREING fit and seal BUT without tooooo much stress.
Some say the solid roofs are cooler etc etc. My 78 with solid panels is cooler than my 87 with see thru panels, best of luck..
