I have a trex-arms ragnarok with the belt slide: https://www.trex-arms.com/store/belt-slide/

If I want to switch to a SL 6354 for the retention (and will be getting the TLR-1 version),  I believe I need the following:
https://www.trex-arms.com/store/safariland-qls-female/
https://www.trex-arms.com/store/safariland-qls-male/

Is this correct?

Is there a cheaper way to get the SL 6354 without the leg rig?  Do I want the leg rig?

Edit** I want the QLS so I can detach to more comfortably get into a vehicle.

Yes,  the receiver plate and the fork.

Also, if you don't have the screws and nuts, you need those as well.

If you need them, I've used the link below multiple times and have always got them quick.
https://www.ebay.com/itm/3-8-Screws-Nut-Gun-Holster-Accessories-Hardware-for-Safariland-QLS-MLS-ELS/173566438928?ssPageName=STRK:MEBIDX:IT&var=473066613583&_trksid=p2057872.m2749.l2649&redirect=mobile

Also, pm sent

6354 is a drop-leg configuration.  The 6390 series is the belt-mounted version.  
I prefer a low ride drop-UBL, so the 6395 model has the holster on a 6075UBL drop attachment.  The other option is a UBL Drop Flex adapter, which is a semi-low ride/drop leg setup that you see a lot of instructors running.  I don’t recommend that you get a drop-leg/thigh holster unless you really need one, or have used one in the past and really like it.  Those kinds of holsters are on the way out, and we’re seeing fewer and fewer people run them in tactical environments.  Most guys are opting for belt or drop-flex mounted guns.  I ran a drop-leg rig from Blackhawk (nylon, not Sherpa) and Safariland for years for both MIL and LE tactical applications, and I’ve wholly moved away from them many years ago, favoring a low ride drop belt position going off either a duty belt or battle belt setup.  If you look at the history and intent of drop-leg/thigh platforms, they really don’t have a lot of utility anymore now that there are a plethora of sturdy carry belts and height and cant adjustment options.  Plus, if you run cargo pants, drop-leg holsters block an entire cargo pocket.  If you’re running a separate gun belt, running any drop-leg platform that straps around the leg will leverage the strong-side of the belt downward while you move, and it can cause your belt to lift up on the weak/reaction side while pulling downward on the strong side.  You have to have a way to attach the gun belt to your inner belt to prevent this pulling/tilt, be it belt keepers or velcro on both the gun belt and inner belt.  

Running QLS on holsters and mounts is also very beneficial, as it makes it easy to swap out holsters for different guns.  If you run an Safariland holster, I also recommend that you look into an attachment that allows for vertical positioning or negative cant of the holster.  The Centrifuge NCP or NCP2 are ideal for running a Safariland holster to eliminate the annoying forward cant.

Thank you.