2003 LB7/Allison 5spd. The truck sat for 10 months over winter(inside heated shop) and while head work was being done. Engine and trans remained in truck. Nothing was touched on the trans,trans cooler lines, radiator or trans cooler. When engine work was completed, fired it up and went for a drive. Within 20 minutes, trans had overheated to the point the DIC read "Transmission Hot" and the alarm chime started. Shutoff and left overnight. Drove back to shop. It was a cool morning so didn't get as hot but almost into the red on Trans Temp gauge. On the hoist pulled the trans to cooler line off, fired up the truck, no oil from the line. The trans shifts fine and goes into lockup. Pulled the trans pan(Mag Hitech) and replaced the internal filter as well as the external filter. This trans has some mods and is equipped with an ATS 5 Star. It ran last summer and made around 10 passes at the strip as well as some daily driving with no trans issues whatsoever. Any ideas as what could cause this?
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