Dennis,
All the misc. parts will interchange and 'drop-in'. See below for two special cap screws needed for Bisley grip frames. Even if switching from a plow handle with internal lock, but you need a standard spring perch. (That doesn't apply to your old Vaqueros, however, none had locks.)
The production change is the ears around the hammer base. But all Bisley grip frames have the tall ears, so no problem for you.
This may be what you saw, it's my bulletin on grip swapping posted numerous times:
INTERCHAGEABILITY OF GRIP FRAMES:
In general: All Ruger SA grip frames including SBH Dragoon, Old Army, Bisley and Birdshead (excluding Bearcats of course) will interchange from the standpoint of the screw pattern from Single Six to Super BH, Old Model to New Model, and even NM to OM.
All the screws, springs and pins can be transferred over from existing GF. The exception is you need the two hex head capscrews for installing a Bisley GF. Or two regular screws if removing a Bisley GF.
Depending on model and vintage, be aware of;
matching the grip frame 'ears'* to main frame,
grip frame projections **.
*GRIP FRAME EAR CHANGES to be aware of: Below are photos of the ears around the base of the hammer The height varies on all grip frame ears slightly but there was one specific big increase. To simplify production in about 1997, Ruger increased the height of the standard cylinder frame mating surfaces on both sides of the hammer 1/16” to match the Bisley model frame ears so any style grip frame could be assembled to any main frame. Therefore the ears on all other grip frames after 1997 had to be made 1/16” taller as well. So there's basically two sizes: as short as .530” pre 1997 and as tall as .590” after 1997 (for example: Original Vaqueros over serial range 56-XXXXX). Measure from the very top edge of the grip panel to the top of the ears. That's why swaps are simplified if any acquired grip frame matches the vintage of your Ruger that you want to put it on.
The grip frame ‘ears’:
** GRIP FRAME Projections shown here pointing to the left just above the two rear trigger guard screws and under where the hammer would be. To fit grip frames with projections to guns w/o the cut out in the cyl frame, just saw or grind off the projections:
Bisley grip parts from Brownells (the links also show Ruger's part numbers):
Grip frame stainless $97 http://www.brownells.com/handgun-parts/frame-parts/frames/grip-frame-prod44165.aspx
GF Blue $128 http://www.brownells.com/handgun-parts/frame-parts/grip-frames/grip-frame-steel-in-the-white-prod12141.aspx
Screws, SS $3 (2 required) http://www.brownells.com/handgun-parts/grip-parts/grip-screws/grip-frame-screw-b-back-ss-sku780001221-12078-28782.aspx?sku=780001221
Screws, blue $3 (2 required) (2 required) http://www.brownells.com/handgun-parts/grip-parts/grip-screws/grip-frame-screw-b-back-prod12143.aspx
Hammer, SS $28 http://www.brownells.com/handgun-parts/trigger-group-parts/hammer-parts/hammers/hammer-assembly-ss-prod55574.aspx?avs|Manufacturer_1=RUGER
Trigger, SS $16 http://www.brownells.com/handgun-parts/trigger-group-parts/trigger-parts/triggers/trigger-ss-sku780001217-12074-28778.aspx?sku=780-001-217
Trigger, blue $16 http://www.brownells.com/handgun-parts/trigger-group-parts/trigger-parts/triggers/trigger-prod12144.aspx
Grips:
Ivory $100 http://www.brownells.com/handgun-parts/grip-parts/grip-panel-parts/grip-panels-simulated-ivory-prod44204.aspx
NOTES:
Always check the screw holes for machining chips left in them from threading the holes and clean them out if present. The two screw holes behind the trigger guard usually have rollover burrs from drilling the hammer pin hole and milling the frame. This will cause screws to break off and/or screw in too tight.
Install all five screws but do not cinch them tight. Align the grip frame edges flush with the cyl frame by tapping with the butt of a plastic handled screw driver. Tighten one trigger guard screw, then front screw and then one ear screw. Then tighten them all.
New Vaquero and NM Flat Tops use a hammer spring with slightly less tension but that has nothing to do with the internal lock. Ruger supplied the new spring due to SASS customer demand. It does not need to be changed for reliable ignition and in fact I prefer it. Especially so when I use it in my Single Sixes with their shorter hammer and resulting less leverage!
