Okay,here it goes(very deep breath)... .
The ETH (HO) motor became available in the 2001 Ram which came out in Jan of 2000.
The 6spd was available for a very short special order run for the late 1999 trucks. The only engine available was the ETC (std) motor.
The 6spd was available again for the 2000 trucks,but in limited supply. Again,the only engine available was the ETC (std) motor.
I first heard of the 6spd back in spring of '97 and it as rumored to have been optional for the 1998's,but that never happened. Then the rumor was it was to be available for 1999... it didn't happen,but then half way through the 99 model year,Dodge let dealers open the order window for only about 2 or 3 weeks. It took about 5 months to build those 99 6spd trucks. The 2000 model year only lasted 5 months because Dodge introduced the 2001's very early. For the 2000's,the trans was available for the first month and a half,then Dodge put it back on restriction,then made it available again during the last month of the 2000 model year.
-Mike