I've never used a bushing driver. I start bushings in with a large plate so that I can tell immediately if it's going to ****. You cocked the bushing and made a crescent shaped indentation. I use a th350 valve body support plate to start most bushings and several transmission parts to finish them in. I guess I should buy a bushing driver set since I do have a press. But I use a flat plate as big as will fit, and start tapping the bushing in. The large diameter of the plate tells me immediately if it is cocking. It's pretty hard to tell if it's cocking when you use a small diameter driver, because it doesn't take much to be off center enough to damage the bushing pretty quick. Find a six inch diameter plate 3/8" thick. It's the best way I've found for beginners to not mess up. I just never upgraded to the professional tools. Bushing drivers are designed to barely fit inside the bushing and barely over the edge. It has to fit perfect or it makes a mess. I install external seals the same way. Using a bushing driver by hand is chancy because if you don't have the tool perfectly in line you will distort it. The best way is using a press that the driver mounts into perfectly. It's a ramble, but I keep thinking about all the times that transmissions have come in disassembled; along with a "complete" rebuild kit and half the bushings are either mangled or missing.