This mod will give you about 4" of extra up clearance for longer shocks and will convert from the stock stem top mount to an eye mount.
You'll need 5 things to complete this:
1) Visit your local Ford Dealer and ask for part #E5TZ 18183A - this is for a 1988 3/4 ton truck and looks like this:
2) new top bolts. I chose grade eight 5/8th" bolts and found them over at Northern Tools. The 5/8th's required that the holes for the shock mounts be bored out a bit, but no big deal. (I think these were only a couple bux)
3) thread lock - GET THE STUFF YOU CAN REMOVE! Yes, there is a difference. Unless you want to drill out the bolts if you ever have to remove the shocks, get the blue locktite...not the red. ($4-5 bux)
4) longer shocks (Mine are Rancho 5000's model 5036 and ran about $40/ea)
5) longer brake lines...but that is another writeup. (about $45/ea)
This mod let me move from 26" extended Rancho shocks to 36" extended shocks.
Begin with the stock tower mount:
Cut out the existing tower mount but leave the spring mount. I've read that others used a Sawz-all to do this. Didn't work at all for me since there is really no space to position it or enough clearance behind the metal to not avoid hitting something. Cutting this out was a royal bitch to say the least.
A tip: use an angle grinder cut these out in two phases. For the first, use a cutoff wheel to cut the upper side and thru the middle all the way thru and toss the section away (the green in the picture below). For the second, use a heavy grade sanding disc to sand the edge down to the frame (without digging into the frame) (the blue with white writing below). This will basically delete the existing welds and allow you pop the chunk off with a claw hammer. When done, paint any exposed metal.
Once it is cut out:
Grab a hammer and beat the hell out of the portion of the wheel well shown below. This will allow the top bolt to fit. This will be on the cab side of the vehicle for both sides. Be sure to check if there is anything in the engine compartment that might get damaged from the hammering.
Now position the new mount so that the shock will remain perpendicular to how it rides on the axle: