Oh the phone with Sara at Lang and this is what I got from her before being passed off to a fabricator for more tech questions.
36 stretch patio orginal is 1595.00
Same firebox size as the 36 orginal
Length is close to the 60" about 54" length
16" cooking grate width (have heard they were 18.5")
It makes an excellent ribs/butt cooker due to the length and width
Both 48 and 36 are 3 week wait time.
Only thing that alarmed me was he said the 36 stretch is under priced right now because they are so new and they are not proven like the 48 is in regards to manufacturing, he did say the firebox will keep up with the expanded size of the stretch.
US Navy. WSM 18.5", Stumps Smoker Baby, SF 24x48 RF, Weber OTG.