Right now I'm running a stock datsun diff in my 1970 510. It's clunking a bit and I've been thinking about upgrading to either a subaru r160 or R180. I'm thinking for now that I'd like to run a 4.11 ratio which the r180 never came in but wondering if I'm going to be limited down the road with an R160 diff if I decide to do an engine swap to something with closer to 200hp+ I'm certainly not launching my 510 or drag racing but I also don't want to worry about the rear diff being a time bomb with an engine swap down the road. At what hp/torque do the r160 diffs start to fail, what numbers can the r180 withstand? It seems like it would be quite expensive to get gears for an R180 diff to swap it to 4.11 so each diff comes with compromises. Ultimate goal would be to do a cv conversion too and I'd really like to avoid buying an r160 now, just to upgrade to an R180 in a year or so.