#1
My guitar is fitted with a regular tremelo. Now I'm replacing the bridge humbucker with a SD SH4.
My question is, do I need a regular one? or is the trembucker needed?

The reason is because I'm buying used and there is only a trembucker version on offer.

Help me out please
Gear:

Ibanez V50 acoustic ( my first love)
Ibanez 442 RTR ( my second love)
Laney Linebacker Reverb 30Watt
#2
I think you need the trem-spaced one if you have ANY kind of tremelo (including vintage and floyd-rose ones etc.).
Easiest way to check is to measure from Low E to High E from center to center and if it measures 51-52mm then you need the trem-spaced one.
Gear:
>ESP LTD FX-400SM
>LAG Jet JM100 with Swineshead Venom (bridge) and Warthog (neck) pickups
>EHX Bigg Muff Pi
>BOSS MT-2 Metal Zone
>Epiphone Valve Standard (Class A 15Watt)