http://www.dotheton.com/forum/index.php?topic=46438
The RD Swing arm measurements are in the above thread.
“Ds7,r5,rd250,rd350, rd400, twin shock dt250
total lenght 18' + 1 1/2 inch for rd400 + 3 dt250
7 13/16 axl spread
7 9/16 pivot
All rds except the 400 run a 17mm axl but there is a 20mm bushing on the sproket side so the axl plates are different left to right the all the dt250 & 400 ive seen are 20mm on both sides
for all the above bikes the pivot bolt is 16mm as is the frame”