Derek, my guess is that a decent local gunsmith might charge about $25 to take off your old stock and replace it with the Speedfeed stock. Unless he's jammed up he could do it while you wait.
It
is the kind of job that's within the capabilities of a careful do-it-yourselfer but it's much easier if you have the
right tools. And they ensure that you don't muck up the gun.
To do the job properly requires two specialized tools. One is
a forend wrench similar to this to remove the nut that secures the forend:
It costs about $20. The other tool is
a buttstock bolt bit, which fits on an extension that reaches down into the dark recess of the buttstock, and requires a handle. The bit looks like this:
The bit costs about $22. You're home free if you already have the extension and handle, but if not you can get decent ones inexpensively at Wal-Mart for about $25-$30, I think. You'll also want a very thin Phillips Head screwdriver to remove and install the recoil pads.
Of course you don't really
need the special tools. I've seen suggestions that a pair of needlenose pliers or other makeshift can be used to remove the forend nut and I don't doubt that it can be done. I wouldn't do it because I don't want to risk scratching the gun or stock taking off the nut, and I won't risk not tightening the nut enough when the new forend goes on. You also can use a long flat bladed screwdriver to take out the buttstock bolt. I've done it but it's very careful work: if the screwdriver slips the bolt slot, it can wedge between the bolt and the stock. Twist the screwdriver hard enough then and the stock cracks.
If this replacement will be a one- or two-time job, a gunsmith can do it cheaper, faster, and with less risk. Your call.