No. The modernized "plastic fantastic" UMP and such use totally different lowers and internals.
The "old style" G3/MP5/HK33, etc. generally all accept the same type of lower assembly, the .308 rifles have a longer "tail" on the back because the stock mount is longer and is held with 2 pins. The 9mm and .223 variants have only one stock pin and are shorter back there. They interchange as a unit otherwise, and the shorter ones work fine on the .308 rifles. The only internal differences are the ejector is caliber specific and some calibers used a different hammer and/or spring, so those need to be changed out if the caliber is changed.
The one exception is the MP5K and SP89 lowers, they do not have a tail at all and use a pin at the upper rear of the lower instead, unique to those firearms. Internals are the same though.
Now, there are several different varieties of "old style" lowers. The standard one found on most older rifles is the metal "SEF" type that used a separate plastic grip on a stamped metal lower. The internal FCG box was the same on all these, Three positions, Safe, Economical, and Fun! (safe/semi/full)
Later versions used an all plastic one piece lower that was injection molded over a sheetmetal liner. They used the same SEF type box inside, but the selector was longer to compensate for the thicker sides of the lower. These had the finger groove grips similar to the stamped ones.
Now we come to the burst lowers, the ones with 4 or more positions and a different internal setup. The burst lowers use internal detents in the FCG box, so the outside of the lower is smooth sided. Different selector, they are also ambi models with a selector on each side. There were two versions of the burst FCG box, one had the ratchet mech in front, the other in the rear. Dunno if they interchange or not, but the rear mounted ones are the easiest/only ones to use with a registered auto sear. These usually have the smooth grip assembly, commonly called the "navy" type.
There are literally dozens of variations in the "old style" HK lowers and internals, especially in the burst pack lineup. Basically, as long as you buy a "matched set" of lower and internal box you can get it to work on any of the old style HK models.