I am replacing my windshield this week and I am wondering if the two windshield spacers that 914 rubber sells is mandatory for proper placement or will the general spacers that auto glass repairmen carry will be fine.

You do want to use the spacers to set the correct height. The glass shops do have some shims they can use, and they may have them, but you are in luck. I was using the factory ones as I couldn't find a generic shim that was available that matched.

The OEM ones were a bit spendy, but I did reproduce these so you can get them for less now. I'll post the GB now to save you some cash.