Pemko has a minimum order requirement. Orders smaller than the required minimum have a longer lead time as we need to consolidate onto a stock order. If you need a faster lead time, simply exceed the minimum order amount.
Pemko 434APKL 36" Automatic Door Bottom with Pemko Prene insert - Mill Finish Aluminum - Full Mortise Mount
The link to the product we are discussing can be seen here:
Click Here
Information regarding the amount of unit that you can trim off has not been provided to you accurately and according to the manufacturer's installation instructions as seen here:
Download File
you would be permitted to trim down 2” from the side opposite of the adjusting bolt and rod. Since the unit has to be ordered anyway due simply indicate the net size that you require because it will not make it any faster or any longer to receive either 40” or the net 38 13/16" life you require.