If you''re racing you definitely don''t want to lock the rear diff. Some people do run lock diffs (spool) in the front on 4wds though. For drifting some people do lock a diff and others dont. I definitely wouldn't lock the diff on the F1 unless you're looking to make a drag car. Locking the diff will make it want to spin around corners.

As for when buying a used R/C I wouldn''t buy one with a locked diff unless it was a rock crawler. Most people use jb weld to lock the diff which is irreversible.

BTW Has anyone noticed that when you use an apostrophe in RCU it adds a second one right next to it which makes it look like you used quotation marks by mistake. For a few days I thought it was my keyboard doing this but then I noticed others having the same problem.