It works ok, but still short on power... I found on ebay a worm drive gearbox motor similar to Andy's grinder, gonna go that route... I'll try these wire bristle drums on it, as well as sprockets like Andy did, hopefully it'll do the job like I want it to.
Digging through the wkend I thought the tunnel was starting to get dry & hard, but it was just my ripper was wearing out & getting dull... welded on a new ardox spike & it's ripping like butter again. The JD850 is just about completely underground... about 4ft, a third the way already!
I sold the RC4WD hoe a few yrs ago.