Got a 71 dt1e running and had a few questions. 
Advice on best sprocket tooth combo.
What racks will fit, at ct interchange?
After 15 minute ride in ga 90 degrees head temp 348 degrees, seem ok. 
Bike runs strong.
Can you put the low fender on a 21 inch front?
Thanks

Std gearing is probably the best place to start 14 : 39 .
AT & CT racks do not fit . Not too many racks out there for DT1 , but they do turn up occasionally .
Low fender is fine with 21" trials tyre . Can't comment on clearances with knobby patterns though .

Thanks

Some additional info. Stock gearing on my '71 DT1E was 14 front 44 rear. I put a 16 on the front since I ride mostly on the street. The 360 has a 39 tooth on the rear, the owners manual lists a 44 rear for the close ratio transmission.
Luggage racks were standard from the factory for the 125 and 175. The dealer could order an accessory rack for the 250 and 360. I don't think many were ordered back in the day. They do come up on eBay occasionally but they go quick. The last one I saw was 3 weeks ago and only lasted a day. (I got it, now I have 4, yes I'm bragging).