The other weekend in between business trips I was able install Byrd Shelix cutterheads in my jointer and planer with the help of a friend. I had been selling misc shop tools that haven't seen much use to raise the cash, and I finally raised enough to purchase both the jointer and planer heads thanks to a great sale price from Grizzly that was matched by Holbren (who threw in free shipping as well).
From reading others experiences I gathered that the jointer head would be fairly straightforward to install, but from my personal experiences with tearing my planer apart I knew that would be a PITA. Much to my surprise, they both went fairly easy, and we were able to get the two machines done in about 4 hours. My friend was a huge help, and we had to re-use some parts that I wasn't planning for, but overall it was a much easier task than I expected. So I thought I'd capture some lessons learned here for folks who might tackle the same task in the future.
For the jointer, the biggest surprise was that the bearings on my Griz G0490 (one of their first models) are different than those in a DJ-20, and they're also different than those shown in the on-line G0490 parts list. So the replacement set that I had on hand were later returned to the store, and we had to pull the original bearings and re-install them on the new shelix head. Other than that it went easily, and after tweaking the tables with the new head I was testing the machine in no time.
The planer was definately harder to do, but it didn't take much more time (probably thanks in part to my previous experience with "repairing" the gearbox). The biggest issue with the planer is the $%#@* gearbox. It looks easy in Byrd's step-by-step document, but my gearbox did not come apart (on either occasion) nearly as nicely as the one in Byrd's pics. The shafts and gears interlock with each other, there are bearings all over the place pressed onto shafts and into the box housing, and the oil seals are tricky to seat properly. Also, I think there's a fundamental flaw in the gearbox that permits the oil leakage - it needs an additional fastener in the upper corner of the case to get a better clamp load on the gasket. Before you start the planer head make sure you have print outs of the exploded parts diagrams, replacement oil (I used 80-90W gear oil), replacement bearings and seals, several bearing pullers (the cheap HF set I purchased had several sizes and worked great), shop rags to handle the grease/oil, a dead blow hammer and deep well sockets to coerce bearings into/out of their housings and shafts, leather gloves to protect your hands from getting sliced on the cutters, and some real estate to lay out all the pieces/parts. If you have some base knowledge of bearings, take your time, don't chip the new cutters, and keep everything neatly organized and you'll get it done.