2003 duramax in limp mode. 6,000 or make an offer

Has a new used transmission and transfer case with about ~200k miles. Have been trying to figure out why it’s in limp mode since install, pretty sure it’s electrical or due to the nbsu.

Has a new rear driveshaft and u joints. Airdog lift pump, rough country 2.5 3 inch level kit and trailer brakes. New headlights and fog lights, fairly new tail lights. Need the money so forced to sell it at this time. Has been hazing a little bit lately but very light, has had the same fuel in the tank for a year and half though and I think that’s the cause. Ran great before the transmission went out 1 and a half years ago and is a work horse. Spent most of its life in Washington so has a little bit of surface rust around the fenders and two 5x2 inch spots on the rocker panels on both sides.

Current codes it’s showing are:

P0700, P0722, P0708, C0055, C0035 and B0159.

Jolts hard into drive and reverse but can drive in one gear and only one due to limp mode