Vernal

Dropping in for some tech talk and advice. I have a 2001 chevrolet 1500 single cab with the stepside bed, standard with the 4.8 Lr4 gen 1 motor and automatic transmission.
I opened up my owner's manual and under the 4.8L section it says 5 speed manual and automatic.
I have been looking in forums and wikipedia and Im not finding any luck finding this illusive 5 speed manual.
I read that one of the manual truck trans can only withstand 250 and yet i know the turbo diesels have a 5 or 6 speed.
Any of you ever heard of a manual trans for the 4.8 or any of the gasoline v8s in the 2001 generation?
I also heard the 4.8 is based off the ls series engines, so would a corvette or camaro transmission have a similar bolt pattern.
Any input would be grately appreciated, thanks for your time.