FWIW & IMHO:
The part no for the redesigned resevoir is 25531140, and I assume that is the same part no as the old design. The part no for the feed hose is 25531141, and I do not know if it is still available.
The return hose is part no. 7828506, and I do not know the validity of that part no. GMPD showed the return hose for $ 21.66, and they showed the GM price as being $ 4.33.
I know that the resevoir is still available as I picked up 1 from my dealer for about $ 34.00, I believe, which was at that time about $ 12.00 above list. I know that the size of the hose that you need is 5/8", and I don't think that standard rubber will work well. Probably should go some of that cloth reinforced rubber hose just for good luck. Probably why GMPD wanted $ 21.66 for it.
Good Luck
All of the above is documented on GM Technical Service Bulletin Nos.
Document ID:
434371, 267583, & 266439.