I am going to do a Detective build for New Vegas and was wondering about any mods that could fit in with the theme. I am mainly looking for Quest, Armour and Companion mods but any and all suggestions are welcome.

Thanks

well, i don't like this detective thing a lot but, a companion i would recommend for sure is Nick Vallentine from FO4 (Tank girl ported) and is amazing.

armors i'm not really aware but Nick provides you his armor when you finish his quests.

as for the quests i don't know any but you could search on nexus, sure you'll find something!

Found a nice Sheriff Outfit you may like to use

Evil Detective Outfit for Males on the Nexus:
Basically a sheriff outfit with some tactical gear and a badge.

Link:

Other then that a lot of the stuff is all ready in game. 
For weapons I would just download a weapon texture enhancement/replacement as the common pistols you associate with those 1950's themed detectives are all ready in game (Revolvers, 1911)

I think you might like the Quest mod called "Autumn Leaves". It requires you to investigate an old library inhabited by machines. Mysteries that need solving!

Spoiler:

Also found this on the Nexus. I think it will go really well with your Detective playthrough.

Spoiler:

Hi, I'm new so i can't post external links so.. i'll say just say it

I think the MNK-RHINO Gauss revolver by leorage on fallout nv mod nexus  will fit your detective playthrough because if you haven't noticed fallout's laser, plasma, gauss weapons. a detective in the fallotu world my use something like it

Downloaded all of the mods recommended and all are brilliant so far, especially Autumn Leaves. Thanks for the responses!

for the weapons i'd suggest

either 357,44 revolver or the sequia. for handguns

or this guys: http://www.nexusmods.com/newvegas/mods/60053/?
http://www.nexusmods.com/newvegas/mods/60096/?

for the rifle id suggest this http://www.nexusmods.com/newvegas/mods/36728/?
or the one from honest hearts complete with the drum mag.

for your office /home
this is the only thing i could find. http://www.nexusmods.com/newvegas/mods/62963/?

I know one of Dragbody's packs has some detective outfits in from other games but there is also this gem I found on the Nexus which I absolutely adore

http://www.nexusmods.com/newvegas/mods/62948/?

Then of course, the 2019 Detective Special from Blade Runner, a replacer for ThatGun. Or you can make it a standalone using the Geck, if you know how. Would make a suitable gun for your playthrough.

http://www.nexusmods.com/newvegas/mods/60053/?

For quest mods, I'd recommend a few. Namely the Someguy Series, NVB 1, 2 and 3, along with the inheritance. War Trash could be good for a detective. Blue Note would make a lot of sense for a detective, it's far more story based than combat, perfect for a more RPG based character. Could try the Tales from New Reno series and Autumn Leaves as well. Maybe DEIMOS could work for a Detective as well. Beyond Boulder Dome would kind of make sense considering how it starts. I'd have to think of a few more, I know I'm missing some that would make sense for a Detective build. It depends whether you wanna go pure RPG mode, which I think would be the most fun.

Anyway, I hope these help.

it might be more for a solder/spy playthough, but could probably for a detective/cop playthough as well,
but check out the STUN - Stun and Tie Up NPCs mod, it puts rope and handcuffs to the game, where you can knock out enemies instead of killing them and just tie them up! it also has smoke grenades too. pretty fun,

http://www.nexusmods.com/newvegas/mods/57446/?