The 2.7 should be easier to find than the 2.5. There are detail differences between them, but I would take what you can get. They tear either from age or as a result of them being difficult to get on correctly when they harden. Keep your eye on the salvage yards. SterlingFixer.com may be able to help. They are the last resource for new old stock I know. There are probably a couple of ways to patch it with a black silicone gasket stuff. I got lucky and found a good one on a salvage car.