Yeah thats right. You can put a Mark iv safety on a Mark iii. I have never seen it done before and I had a hunch it would work. So i tried it and here are the results.

whoa!  I gotta do that!

thanks for your tinkering!

Here is an exploded diagram of the mark iv and a list of parts.

Parts you need
1-#20(safety) or modify your mark iii safety to accept mark iv lever(I modded my mark iii safety)
2-#22(safety lever-left) or after market safety lever(I used tandemkross cornerstone)
3-spacer and screw for right side(not pictured in diagram, I ordered these from ruger)

* PARTS SO MARKED MUST BE FACTORY FIT
Key No. Part Name
* 1 Grip Frame
2 Frame Lug
3 Receiver Frame Screw
4 Bolt Open Stop Spring
5 Trigger Spring
6 Trigger Spring Plunger
7 Bolt Open Stop
8 Trigger Bar
9 Trigger Bar Pivot Pin
10 Trigger Pivot Pin
11 Magazine Latch
12 Magazine Latch Spring
13 Magazine Latch Screw
14 Sear
15 Sear Spring
16 Hammer Bushing
* 17 Hammer
18 Hammer Strut
19 Magazine Disconnector Spring
20 Safety
21 Spring Plunger for Auto Safety
22 Safety Lever, Left
23 Safety Lever, Right
24 Mainspring Housing
25 Hammer Spring
26 Hammer Spring Plunger
27 Latch Spring
28 Latch
29 Bolt Stop Pin
30 Bolt Stop Thumbpiece
31 Left Grip Panel
32 Grip Panel Screw
33 Right Grip Panel
34 Magazine
35 Lug Retainer Screw
36 Magazine Latch Plunger
37 Sear Pivot Pin
38 Hammer Strut Pin
39 Bolt Stop Thumbpiece Screw
40 Trigger Pivot Retainer Spring
41 Bolt Stop Retainer Pin Retainer
42 Safety Detent Spring
43 Trigger

I also made and knob for the bolt from a stock stainless machinery knob. Drilled, tapped, and installed with red permatex.