I missed the beginning of this thread, but I wanted to report my exerience
with a shrunken tonneau. My situation was with an Austin Healey BT7. The DPO
had purchased a new tonneau (Mitre Trim, made in England) for the car but only
fitted it to the rear Tenax studs. It sat in that condition for about four
years. After purchasing the car, II tried stretching it to reach the dash,
and discovered it fell about 2 1/2 inches short of the destination. This was
an essentially new cover and the thought of trashing it pained me. I went to
an auto upholstery shop and they extended the length of the tonneau by
installing 2 1/2 inches of additional material just behind the front seats.
The new material is a close match to the original stuff and looks like it is a
part of the original design. The tonneau also fits very well. Cost was $30.
1960 AH Sprite
1961 AH BT7