4-speed pushing a 4-door & 35" tires. That's about as much "load" as you can put on a trans & mine works like a charm. Don't need crawler gears 'cause the torque multiplication is the goods. If you run an auto, there's a few things to keep in mind: No bump-start = run a dual battery system (or have one of those "charge packs") & carry a spare starter (ask me how I know). And, RUN A LARGER TRANSMISSION COOLER, or a second trans cooler in-line. It doesn't need to be a monster, but the stock cooler will be inaddiquate for rock crawling, or larger tires. Torque convert's going to be working harder - which is totally fine as long as it's supplied with cooler oil (I believe around 170*). You can re-use the old trans cooler as a power steering fluid cooler (also needed with larger tires), or an engine oil cooler.