The part number you were looking for appears to belong to a different Delta miter saw - MS250 10" compound power miter saw. You need to look for parts for 36-075 diagrams here:
It looks like the two parts - left and right halves of the handle - are identified by their individual Delta part numbers (see a blowup of the relevant part of the diagram attached below)
On that diagram:
part #134 (Handle, left part) is Delta Part #1347145 part #137 (Handle, right part) is Delta Part #1347147
The complete set of two parts for the handle of this saw is Delta Part # 903589
As luck would have it, ereplacementparts has one of the right handle halves left in stock - could you use it without its counterpart?
The left part as well as the set do not turn up easily but if you search for it using the right part number, it eventually might on eBay or elsewhere online. Perhaps, a call to ereplacementparts may help you find it, too.