the Plano grills are designed to overlay the existing molded grills...they overlay EXACTLY, in position, on the model for which they're designed (I used them on a LifeLike E8B unit as well...with the grill designed specifically for it)
The method for attaching them is left up to the individual...I've found a method, through trial and error, that works for me...I use Gorilla Brand super glue to tack the grill into correct position...then, very carefully, use a finely chiseled end of a toothpick to apply extra thin super glue all along the perimeter of the grill edges...this keeps the extra thin glue from getting on plastic detail and allows the glue to creep along the join line; the extra thin super glue does have some surface tension so it wants to creep along the join line.
When I first started these mods, I only tacked the grills on in various places...I'd find, that with less-than-perfect handling of the unit, I'd pull the grills off; shipping to friends also had the effect of popping one or two of them off as well (I've sold a set, and I've done a few sets for friends back in Texas)
Here is a pic of the Plano grill, designed for the LifeLike E8B, on the unit...you'll notice that I used GMM stirrups on this one also...as you said, it makes a world of difference.
in addition to this freight schemed unit....I'm also doing 5 warbonnet F7A's and 4 warbonnet F7B's....also, in the waiting line are an A-B-B-A set of the newest release warbonnet F3's, the ones that fit my era perfectly.
The carbody openings on the F3 units are just a bit different that the F7s...so I'll have to create a new pattern for the decal stripes that I'll use for these.
Your comment, yesterday, about the paint under the grills, fore and aft of the warbonnet seperating strip has me considering a sheet of red decal strips !
Here is a pic of the freight unit with the cut lever added, and the ATSF-style opening cut out for the air and MU hoses.The Z scale coupler is also added here, although I'm going to raise it just a tad with a slightly thinner shim (just visible as a white piece inside the coupler pocket...it will be painted black, just like the rest of the pilot. Since this mechanism goes way back, the coupler 'holder' clip device that attaches to the split frame is different than the newer mechanisms, and needed a different approach to add the z scale coupler.
This scheme is, definately due for a re-issue, by KATO, on the new decoder-ready mechanism!
Thanks for looking,