Reviving an ancient thread here.
I found some really useful information in thread, especially from HondaDude, and have a few things to add that may help someone else in this situation.
A little background, I recently picked up a 2003 2hp BF2D, it did not run and the "gear box was locked up". I was able to get the motor running well with in a few minutes simply by cleaning out the carb bowl, however there was obviously an issue with either the clutch or lower unit.
I removed the lower leg and was able to watch the shaft spin free by rotating the propeller so I figured it must be the clutch issue discussed in this thread. After completely disassembling all of the "stuff" off of the power head I was able to remove the clutch housing. It was immediately obvious that water had penetrated the housing as the outer clutch assembly that fits through the bearing in the lower part of the housing would not spin at all and there was some light rust and obvious corrosion on the assembly. For fun, since I was hiding from my spousal unit in the garage, I decided to try and free it up with a combination of WD-40 and some PB Blaster penetrating oil. Surprisingly that didn't immediately work so I spray a few ounces on it and decided to let it sit for a while. In the mean time, since I was confident I could have this outboard running well, I went inside to see if I could order the bearing and discovered that the part was listed a "unavailable". (Part #10 on the diagram). My parents later showed up at the house and much to the womenfolk's dismay my stepfather and I decided to see if we could free up the bearing, which we did however it was a little gritty and it was obvious that it was going to need to be replace. Using HondaDude's advice above I knocked out the bearing using a punch which was pretty easy. Frustrated by the "unavailable" status of the bearing I began searching the web for any info I could find. Eventually I found a parts sheet that listed the bearing without a Honda part number but it had (6004) in parenthesis. I quickly searched Amazon for "bearing ISO 6004" and found a bearing with the same dimensions in a few different versions. I decided to order the sealed version which looked most similar to what I had removed 6004-2RS. I really needed to get the outboard back together before our family vacation to the beach as I wanted to take my son crabbing, so the next day not wanting to wait on Amazon I stopped by a local bearing supply store and with lots of excitement and flailing arms told the guy about the outboard. I was quickly chastised about buying cheap Chinese bearings on Amazon and he sold me a Koyo bearing made in Austria or $16. I took it home, pressed it into the clutch housing using a small block of wood and a hammer and reassembled the outboard. It ran great... really, really good.
Since I basically had $16 into the motor I decided to order a new outer clutch assembly, the housing, new clutch friction plates off the internet for about $88. Figure I'll replace the entire clutch assembly with new parts over the Winter. But for now the $16 fix worked great pushing around my Zodiac all week on the Bay at Ocean City, MD.
When the new parts arrived I discovered that the outer clutch assembly design has changed a little; there is now a second Circ Clip holding the bearing on the bottom, there is no longer a capped hole where the shaft fits into the out clutch, and the assembly ships with a KOYO brand bearing ISO 6004-RDD. I quickly looked this bearing up and can't seem to find it anywhere; maybe it is OEM specifically for Honda. Anyway, bearing 6004-RD seems to be the same thing. The difference between the 6004-2RS bearing that I used and 6004-RD is that the RD is a "low torque" bearing.