MoreTextures

Go into the vehicles.meta and add/edit the following on the CVPI's entry.
<flags>FLAG_HAS_LIVERY FLAG_EXTRAS_REQUIRE FLAG_EXTRAS_STRONG FLAG_LAW_ENFORCEMENT FLAG_EMERGENCY_SERVICE FLAG_NO_RESPRAY FLAG_DONT_SPAWN_IN_CARGEN FLAG_REPORT_CRIME_IF_STANDING_ON</flags>
      <type>VEHICLE_TYPE_CAR</type>
      <plateType>VPT_FRONT_AND_BACK_PLATES</plateType>
      <dashboardType>VDT_GENTAXI</dashboardType>
      <vehicleClass>VC_EMERGENCY</vehicleClass>
      <wheelType>VWT_MUSCLE</wheelType>
      <trailers />
      <additionalTrailers />
      <drivers>
        <Item>
          <driverName>S_M_Y_Cop_01</driverName>
          <npcName />
        </Item>
      </drivers>
      <extraIncludes />
      <doorsWithCollisionWhenClosed />
      <driveableDoors />
      <bumpersNeedToCollideWithMap value="false" />
      <needsRopeTexture value="false" />
      <requiredExtras>EXTRA_1 EXTRA_2</requiredExtras>
      <rewards>
Note that this was originally intended for F5544's Dual Lightbar models, so you'll likely need to change it to only EXTRA_1 or 2 depending on which it is.

Open Trainer > Bodyguard / Ped Spawning > Select Model > Scroll Down to S Peds 2 > Go left until you find s_m_y_swat_01 > Press your trainer's usual confirm button > Spawn Bodyguard in previous menu.

The entry doesn't actually exist already if that's what you're trying to find, you can't access the existing ones, you have to add it yourself with the entry I had previously posted.

Do you have your PostFX setting above normal in the options menu? It won't do much otherwise.

Open Trainer > Bodyguard / Ped Spawning > Select Model > Scroll Down to S Peds 2 > Go left until you find s_m_y_swat_01 > Press your trainer's usual confirm button > Spawn Bodyguard in previous menu.

As Starmix has already mentioned, 2 cards does not mean twice the VRAM, please don't buy a new GPU for this reason, you will waste your money.

Just to avoid confusion here, dragging and dropping a carvariations.meta in will also overwrite it, you need to copy the text from one to the other manually.
All though it was likely just a typo so no worries. Good luck modding!

You're right, I was not drag and dropping. I was replacing... FML... Thanks

Thank you so much for your answer. You did indeed solve the porblem. 
 
Thank you again!!!!

You likely need to add a carvariations.meta entry for police2 in mpluxe2's dlc.rpf.
This is what you'd add specifically:
This is most likely correct but it depends on the model, as it's hard to say with a Federal Signal lightbar as that's pretty generic, as it could also be sirenSettings 2 or 13 among others.
If that doesn't work, you may want to link the vehicle mod you're trying to install and/or a screenshot of the issue.

Got it, than you for all the help man

Oh, Holy crap! I had the PostFX turned way down to Normal, Didn't think it was one of those things that mattered! It completely changed everything! Thank you soo much!

Be sure that your PostFX & Shader Quality is at ultra.
I'd also recommend installing either RadianceV or Improved LEDs alone rather than both at the same time.

I'm aware, but because the OP is asking about the lights not aligning I'd assume whatever he downloaded didn't include one. It's usually either 1 or 13 in most cases anyway though.

That worked, Not sure why it didn't the other way.... Thanks for all the help!

I just recently did this myself. I'm not 100% sure of what exactly I did, but I took a shot at using the carvariations entry from whatever vehicle I was replacing it with and just overwriting the POLICEOLD2 entry and the changing the names where appropriate, and it seemed to work.
The only thing I personally don't know (and I'd love to know the answer if anyone knows) is how to either add or remove the rotators from certain cars like the POLICE and SHERIFF models. The cars I have installed there actually have LED lightbars, but both the LED lights and the rotators show up, and I have no idea how to remove the rotators LOL.

Yep, that's exactly it. I added that flag because I wanted to make sure that when the cars spawn randomly in the game, that they include all of the lightbars and push bars and such. Is there a different flag to do that?

You need to add a carvariations.meta entry for policeold2 in somewhere like mpluxe2 (Or where the model is if a carvariations.meta exists perhaps) with the lightSettings at 1 and sirenSettings at 13 (This is what most CVPIs/vehicle mods will use, but it depends on what you replaced it with).
You'd need to add this specifically:
 
This sounds like you have FLAG_EXTRAS_ALL in the vehicles.meta entry for that vehicle. You can find the Sheriff's entry in the update.rpf vehicles.meta.

You could use something like FLAG_EXTRAS_REQUIRE, followed by inputting all of the extras in the <requiredExtras></requiredExtras> line a bit below the flags, (e.g. <requiredExtras>EXTRA_1 EXTRA_2</requiredExtras>) however GTA V will only pick 1 random extra from the list at a time (And at that point you might as well not use the flag at all unless you want to avoid slicktops).
I'm not sure if there's a way to include every extra and at the same time excluding 1 or 2 to not be with each other sadly, there could be but I just don't know it.

Mainly I just want to avoid slicktops, so your advice is perfect, thank you :-)

I'd recommend giving Keep Calm a try.

Ok
BRO THANK YOU SO MUCH 

(Even though I put this in the previous thread I'll just put it here anyway.)
Have any .meta entries you had in your update.rpf been overwritten, as the game wipes it for almost every update (All though add on vehicles typically don't touch the update.rpf anyway)?
What's more likely is that you've hit GTA V's vehicle cap, which you can edit in your update.rpf's gameconfig.xml.
Editing your max vehicle amount in the gameconfig.xml:
Navigate to update.rpf\common\data\ - Open the gmaeconfig.xml in Notepad/Notepad++ or similar.
Change:
<PoolName>Vehicles</PoolName>  <PoolSize value="300"/> To:
<PoolName>Vehicles</PoolName>  <PoolSize value="450"/> And change:
<MaxVehicleModelInfos value="310"/> <MaxExtraVehicleModelInfos value="100"/> To:
<MaxVehicleModelInfos value="450"/>                    <MaxExtraVehicleModelInfos value="200"/> Then put the gameconfig.xml back into your update.rpf.

Have any .meta entries you had in your update.rpf been overwritten, as the game wipes it for almost every update (All though add on vehicles typically don't touch the update.rpf anyway)?
What's more likely is that you've hit GTA V's vehicle cap, which you can edit in your update.rpf's gameconfig.xml.
Editing your max vehicle amount in the gameconfig.xml:
Navigate to update.rpf\common\data\ - Open the gmaeconfig.xml in Notepad/Notepad++ or similar.
Change:
<PoolName>Vehicles</PoolName>  <PoolSize value="300"/> To:
<PoolName>Vehicles</PoolName>  <PoolSize value="450"/> And change:
<MaxVehicleModelInfos value="310"/> <MaxExtraVehicleModelInfos value="100"/> To:
<MaxVehicleModelInfos value="450"/>                    <MaxExtraVehicleModelInfos value="200"/> Then put the gameconfig.xml back into your update.rpf.