completely new to CB and I have a black cab and an LDV pilot that I want to put rigs in and looking at each vehicle I think they need different twigs, what are your thoughts?
It really depends on what you want to gain with the antennas (pun intended) and how you want to mount them. There are numerous options out there and although some are clearly intended more for big commercial trucks than smaller vehicles, at the end of the day, the overall performance of any antenna will depend more on where and how it is mounted on the vehicle than the antenna itself.
In other words, technically speaking, you could use the same antenna or different antennas on both vehicles and get the same or completely different results simply depending on where and how it is installed.
The general rule of thumb for peak antenna performance is based on clear line of site. The higher it is mounted on the vehicle with the fewest obstructions, the better. Of course, this isn’t always practical, as you will have height limits for mounting an antenna on any vehicle, so location does need to be carefully considered.
This is where the type of mount is important. There are magnet mounts, window mounts, mirror mounts, stud mounts, fender mounts, and some antennas will be designed to work best with specific types of mounts.
And yes, the choice of CB antennas and mounting hardware will depend somewhat on the type of vehicle to which you will mount it. An antenna such as the Tram TBC6 or TBC9 is designed more for an 18 wheeler than a minivan, whereas a Midland 18-258 Glass Mount CB Antenna is designed more for a minivan than a hauler.
Everyone will have their preference of course, and you will probably get a dozen different recommendations based on personal experience with one antenna/mounting kit or another.
With so many options and choices, you will need to first decide where you need or want to mount it on each vehicle, shop around for an antenna that best fits the location and mounting requirements, and fits your budget.