A novel Heater fix question

[Chexi]

So my heater went last year. I purchased the Ford LTD heater, which is very close, but the exit and entry pipes are a little off, requiring a little Dremel magic. This I get. What I need help with is locating replacement insulation to go around the heater. The standard stuff I found at Lowes is too thick. I suppose I could shave it down, but I'd rather have an even surface, as there is not that much clearance. Any ideas where to find a suitable (and thin) insulator (I think it's just for shock absorbtion)?

[johnboyy7]

Mine came with the heater from oreileys.

[Chexi]

Did the one you got from O'Reilly's also fit a bit off, or was it a perfect fit? If it's a perfect fit (meaning the intake out outflow lines lined up perfectly), maybe I'll just buy another one and consider the first one I bought a sunk cost.

[DanielC]

Just cut the foam insulation to fit, or get the O'Reilly's core. Your choice.