The RT industries solid state upgrade is proud to say that it is pulsed just like the original.
I built my own solid state version for about $4 and it is 5v steady.
Some people say this is not a good build because it can fail to a +14v situation, but I've never heard of that happening and I'm not even sure it's right.
In any case I put a fuse in line with my guages which would blow before they got onto a 12v feed, so I think they are sufficiently protected.