Hein at DIYvan shares a product that will help improve thermal/acoustic performance of a Promaster 

Order our NEW Promaster filler cover pieces for holes in the lower wall at diyvan.com/pro....
159 Wheel base panel kit contains:
12 house shapes
2 kidney shapes
2 rectangular shapes
136 Wheel base panel kit contains:
6 house shapes
2 kidney shapes
2 rectangular shapes