I use flex a lite fans, I've always had very good luck with them, none have ever failed; i keep my pickups at least 10 years. I ran one 15 years, still going when I sold it.
On a 1999 Ram, this is an easy install. As on all vehicles, you'll have to remove the radiator first, (I'd highly recommend the diesel radiator, or otherwise heavy duty radiator, when you have it out, why not?) That done, you can then undo the big nut holding on the fan and fan clutch. You'll need a rubber strap wrench, this grips onto pulleys, they are very cheap at any tool store, sears or lowe's, etc. With a tight grip on the pulley- I rest the wrench against another pulley- then you take a big crescent and put a pipe on the end of that for extra leverage- and remember that big nut is reverse threaded (take off clock-wise) and take that big nut off. After the big nut is off- everything else is cake. Take out the fan and fan shroud. Then install your flex a lite fan (get the biggest CFM that will still fit on your new radiator surface area) to your new radiator. Then install the both where the radiator originally fit. Hook up the electric, very easy with flex a lite's instructions, and you are set!
jdb, Ft. Hood, TX
1999 Dodge Ram 360 V-8, diesel radiator, 180 degree thermostat, flow-kooler high perf water pump, automatic, tow package (stock tranny cooler removed for one 3 times the stock size, fits in same spot), 10,000 mile engine oil changes- non synthetic oil, open element K&N, Flex-a-lite monster dual electric fan, three small electric fans in front of A/C condensor, cab high topper. Moved to Fort Hood this past summer: pulled a GCWR 16880 pound trailer in 105 degree weather - ran max water temp of 205. No blown head gasket/trans problems/pickup is fine.
1998 Jeep Wrangler, 2.5 4 cyl, 5 speed, 6 cyl radiator, 2" lift, 31" tires/rims bought used, other mods as above, more mods (lockers, rear dana 44) hopefully coming.
2000 Jeep Grand Cherokee, mods as above, 150,000 miles.
2003 Jeep Liberty, mods as above, with the exception of 185 degree therm. to get CEL to stay off. (still working that)
1937 John Deere model "B" tractor, hand start, restored, .150 over, alum pistons, crankshaft has never been out of the tractor, no thermostat or water pump stock, 150 degree water temp, K&N intake, 3 point hitch, double seat, umbrella.