I added a skidsteer thumb to my PT-425's minihoe. The thumb, originally 16" has since been cut down to 12.5" long. Here's some photos of it in the Gallery, before it was shortened:

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 I'm VERY pleased with it, even though the thumb is currently too long (16") and needs shortened. We decided to try it before deciding how much to cut off, and it works quite well even with the long thumb -- it just gets in the way a bit. We've now marked where we want it cut, and my friend will detach the thumb and have it cut down to size...

I also decided not to reinforce the boom./dipper stick at this point, but to watch it closely for signs of flexing. I really think PT pucker will kick in on a 425 before it stresses it too much, but time will tell...  If you're using a heavier 1430 or larger, I think you'd want to reinforce the boom to keep it from twisting when picking up logs and such.  I'd be more concerned about twisting than side-to-side {where's there's small gussets already) or up and down stresses.

This is just one more example of what the versatility and mobility of a PT will do. While a CUT/SCUT with a backhoe and thumb could grab the material, it can't carry them to the brush pile. You'd have to lift the stabilizers, "park" the bucket, move to the front seat and use the FEL...

We'd just pull them out until they began to get in the way, then grab several at a time, haul them and pile them, then pull more... without ever stopping, leaving the seat, etc. Before, we'd have to switch to the grapple bucket to pile the brush. Also the minihoe with thumb will put the brush up on top of the pile, which you can't do with the grapple bucket...

If you're going to be clearing undergrowth -- IMO, don't hesitate to put a thumb on your mini-hoe! You'll be glad you did. Soils, soil condition (moisture, etc.) and the type of brush will determine what it'll just pull out by the roots, but we could pull out wild hedge up to about 3" in diameter in this moist soil. With larger ones, we just used the bucket to dig it out out with its curl, or dug as needed in front and back...

This is the vendor on eBay where I bought the thumb:

http://stores.ebay.com/SKID-STEER-SUPPLY-CO

I want to point out a couple of things:

1. The 16" thumb shown in the eBay listing is not the exact one that I received. My 16" thumb had 5 teeth, instead of the 7 shown, and we cut off two of those 5 to shorten it...

2. The mounting brackets for the thumb are wider than the boom of the 425's minihoe, so they'll stick out slightly on each side. You'll need to "fiddle with" the exact alignment to get the bucket teeth's to mesh correctly with the 5" wide thumb. I have mine set to where the side edges of the thumb will go between the bucket teeth, allowing the two to close as much as possible, yet not "pinch" at the ends of the teeth. The sides of the thumb go down between the teeth, as shown in the linked closeup picture below. Because of the irregular location of the teeth on the PT bucket, this meant that the thumb mounting bracket is not exactly centered on the boom -- it sticks out about 1/4" more on one side than the other. The side shown below is the shortest overlap -- the bracket sticks out a bit farther on the other side of the boom. I just use the thick spacers (similar to thick washers) that are provided with the kit to make sure the bar that braces the thumb stays centered on the boom...

Enough for the obligatory "notes, cautions and warnings" -- if you still install one, I think you'll be just as pleased as I am with the results... I'm anxious to see what it will do with stone for the retaining wall I've been planning.