My ARF is about 10 years old and is the old style with the rubber band wings. I have since converted the wing to bolt on much like the new ARF.

Main gear
Look in the radio compartment. In front of the servo tray and behind F-2 there is a squarish area. Cut a piece of 1/4" birch plywood this size and epoxy on the floor. Add 3/8" triangle at the ends against the fuselage doublers. Use a 60 size aluminum gear
http://www3.towerhobbies.com/cgi-bin...?&I=LXJ924&P=7
This is the one I used . . . http://www.horizonhobby.com/Products...?ProdID=HAN160
and using holes in the gear, drill - tap four 1/4-20 holes down through the fuselage directly into the plywood. Put thin CA on these threads to reinforce the threads. When dry - retap. Mount the gear using Dubro 1/4-20 nylon wing mounting bolts.

Tail Wheel
On the tail locate the rudder vertical hinge line and extend this down through the center of the fuselage bottom. Epoxy a piece of brass or aluminum tube just large enough to clear 1/16" music wire up through this area as a support for your tail wheel wire. This tube will be along the elevator pushrod so pass it on the side of least resistance. The top is anchored in the solid balsa of the elevator and the bottom is anchored into a plywood reinforcement epoxied onto the bottom of the fuselage. Watch your weight back here. Use a Dubro 40 size tail wheel bracket.
http://www3.towerhobbies.com/cgi-bin...?&I=LXD850&P=7
and make a longer new 1/16" or .062" music wire piece for the tail wheel using the wire that came with the bracket as a pattern. This new wire extends up through the tubing in the fuselage and turns at a right angle into the rudder in the area of the control horn. The right angle must be bent after the wire is inserted through the fuselage. Drill the rudder for the wire and prepare the rudder and vertical fin for the CA hinges and CA Glue. Use epoxy around the tail wheel wire where it inserts into the rudder. Use the piece of plywood to reinforce the area of the bracket to mount the bracket with the screws provided.

I used 3 1/2" Dave Brown main wheels and a 1" Dubro tail wheel. I used hex socket head screws for axles on the main wheels.

The front of the landing gear is at the leading edge of the wing.
The battery and radio are up under the fuel tank. I moved the receiver antenna out the top of the fuselage so it would be away from the main gear.
It looks like it came from Sig as a tail dragger.