Sure can, but. The L/U converter is an inch longer than the non lockup converter so you need second gen flywheel housing and starter, so most folks would ruther use a 47 as there were also other upgrades. If interested in 518 lockup you would need a lockup input shaft, reaction shaft support, and valve body. The 727 can be converted over also but it's a little more complicated.

 

ps, the 727 lockup conversion is only more complicated because of the valve body, chryco never made a 727 electrical controlled L/U valvebody, I would try the hydraulic controlled body. I THINK you could use one of the 904 electrically controlled valvebodies with a little work, these were called part throttle unlock by chryco. I'm working on one of these bodies right now, when it's done next year I'll build a 727 diesel lockup. Funds for the converter is the holdup right now.

 

whether you buy a 47rh or convert a 518 if funds allow buy an aftermarket hd input shaft, the hollow lockup shafts are weaker than the equivalent non lockup shafts. I know of 2 local boys who twisted off the stock lockup shafts in a stock truck, both times it ruined the pump too. Some people call them billet shafts but the stockers are also billet shafts, then carburized (case hardened), all that means is it's whittled from a solid chunk. The aftermarket ones you want are alloy, something like 4340 chrome moly. 4320 and carburized would be better but don't believe they're available.

 

618, 47rh are the same tranny, just different names. 618s (47rh) big upgrade is the double wrap rev band, this can't be retro fitted to the 518- 727.