The #45 works a treat as a tongue and groove plane if only a bit of a mess to configure (they are so dang cheap, you could get two bodies and leave one set up with the tongue blade all the time!). Vintage #48s are also plentiful with vintage #49s not so much. Keep an eye out for the Union brand equivalents as they are just as good as vintage Stanleys (oh, by the way, some vintage Stanley’s ARE made by Union but we shouldn’t delve into the sordid details here, this being a family show and all). Also, the vintage #48s were designed to center on 7/8″ stock, not 3/4″ but they will work just fine on the 3/4″ stock. Just keep track of your face sides and reference the fence accordingly. The modern version sold by Lie-Nielsen is a real hoot to use and is made to center on 3/4″ stock. Its single blade is a bit easier to adjust, more like the old wooden buck-tooth match planes but you may not want to spend the money.

Also, vintage #48s should have been sold with THREE blades, not just two. However you will seldom need the 5//8″ that is probably long since missing. I believe the stock blade size is supposed to be 5/16″ and that is a common size for the #45 and #55 crowd so you can easily find replacements except that they will probably have an extra notch the #48 doesn’t need. Still works fine. In fact, you can order brand new replacement blades in various sizes direct from Stanley if you are so inclined. They will work just fine.

To put things into perspective, if the Stanley #71 & 71-1/2 are the most USEFUL of the joinery planes, the #48 and #49 are among the most FUN of the joinery planes.