CHanging rear end, paccar motor

[Lonestar10]

Pulls much better but it needs a trip to hagg and rawze something's not right with it. Had 17k on bed yesterday and with 550/1950 it couldn't hold 65 going over some very minor hills and when accelerateing when empty feels like it's dragging it's heels above 45mph. I know I'm not pushing much air as I might wif some gravel off a shoulder where a flatnose throws up a cloud behind me.