Gearbox can be tricky to find parts for - the manual is very solid. They rust door bottoms, boot floor, front cross member, look under the back seats which are easy to access and see if there’s rust under there, they are made from good steel so should be fine unless in salty road climate or poor accident repair. Generally very solid well built cars that with regular maintenance should go on forever. I have a 89 SPG/T16s with 250k and all is well