All of the full size pickup trucks come in 1/2 ton, 3/4 ton, and 1 ton varieties.

Ford has the F-150, F-250, and F-350

GMC and Chevy..... along with Dodge all have the 1500, 2500, and 3500 series. 

You could probably get away with hauling safely with a 1/2 ton truck (smallest of the full size), and no, you don't need to go diesel, cause 1/2 ton trucks don't come in the diesel variety.  

PLEASE, whatever you do, just don't get a Jeep cherokee or a Dodge durango type vehicle.  I see so many people driving those things around with horse trailers, and  it is just unsafe.

Toyota has come out with the tundra, and I'm not familiar with that type of truck, but I have heard that the transmission isn't designed to take the abuse that a towing vehicle will put on it, but I dont know if that was true, or if they have fixed the problem.  If you plan on someday getting a bigger horse trailer, you should get a bigger truck now. 

Just take a look at towing capacities from the various trucks.  At horse shows you see the big three: Dodge, Ford, and Chev/GMC.  I don't think I have ever seen a Tundra at a horse show before.

Take into concideration if this is going to be strictly a towing vehicle, or your everyday ride

I think it would be helpful to know how often and how far you will be towing?

I think any of the "1/2 ton" models from Toyota, Nissan, Ford, Chevy, or Dodge with the appropriate tow package will be rated above your intended load. Most trucks in this class will be rated to tow 7,000-9,500 pounds.

With that said, for not much more money you could move to a "3/4" ton class of truck that would give you even more towing capacity and most likely a better "feel" behind the wheel. Personally If I was going to be towing your setup with any regularity, I would opt for a 3/4 ton. If it was only for occasional hauls over fairly short distances and it was my daily driver, I would be fine with a properly equipped 1/2 ton. You certainly don't NEED diesel. Diesels are great for towing and in places like here in CO The extra pulling power is very very nice on the mountains, but for only very occasional towing usage a diesel probably won't make financial sense. 

Tundras have been around since 2000, They are coming out with a complete redesign in 07. This will be a larger truck with a higher towing capacity. I don't know yet if it will come in both a 1/2 and 3/4 ton variety, but I do know its going to have higher ratings than the current model. I actually own a 05 Tundra. I tow with it a fair bit, but not usually horses, mine has a tow rating of 6,900lbs. I tow a 4,500lb boat with it, it does fine with the boat but if I needed to tow that weight every day over long distances I would probably want a larger truck. I see Tundras towing 2h trailers with some regularity, but It doesn't surprise me you won't see many at shows and the like, because those people probably tow a lot and opt for larger (mainly 3/4ton+) trucks. Again, I think it comes back to your intended usage.

 -Flush

Words of wisdom....

Had a 2 wd ford F250,got stuck alot,got a 4x4 f250 instead of a 4x4 F350 (talked out of it by dealer) pulled alot of miles,Got a bigger trailer,needed a bigger truck.Got a F350 CC 4x4 very happy.

I used Durango and Cherokee as examples because I have seen a lot of them hauling way too much weight in the past...

But here comes the "bigger is better"

In all actuality you SHOULD have a vehicle that weighs more than your trailer.  Its just physics.  Car weighing less than trailer isn't going to stop said trailer if the trailer breaks go out.... And it can/will happen at some point in time.  When I first bought a 2 horse sundowner, it had the 5 prong plug, which I had to use a 7 prong adapter (that I got from the dealership) to plug into my 3/4 ton Powerstroke.  Well I didn't notice it until I was headed down a STEEP hill that the adapter was no better than a pile of bull puckey, and it had fallen off, so no power to the trailer breaks. 

A fully loaded 2 horse aluminum trailer weighs a lot more than you think when the breaks go out.  The truck handled it fine, but I couldn't help but think what would have been the scenerio if I were in a smaller vehicle.

Needless to say the next day i went back to the dealership, and they changed the 5 prong to a 7 prong, free of charge.

To all their own

where do these guys come from???  boy im sure glad i got my 6700# diesel to pull my 6000# trailer, wait how did i pull it with the trailblazer then?  and what in the world would i use as a truck if i get a really big LQ?  oh thats right, the class 7 tractor i drive at work comes in a little over 12000#............

Theres my friend, I wondered when you would answer up!! HA HA

Yea...Our ....opps My wifes first Durango had a 4.3L and a tow rating of 6500#'s...She towed over the Willamette Pass several times....no problem. She went and got a new "05" Durango with a HEMI....and a 8,000# + tow limit. They both behaved well. I tested them both before I sent her down the road with them and felt no ill handling problems with either. So......I would recomend a Durango or equivilant for this application....It is in the tow rating....I see duallys that are overloaded and are unsafe, if they have to make a quick decision look out!.... It doesn't mean duallys are unsafe.

that is the point I was trying to make.  Any vehicle will be unsafe when overloaded.  I see it all the time around here.  I saw a sedan towing a 2 horse once...

Geeeezzzzz  You guy's are sensitive

wow.... 

I've just come into this fourm in the last few weeks.   It has been very entertaining, but sometimes I think many of you REGulars are just out to start cat fights as oppose to just helping people out.

i fail to see how correcting erroneous information (PLEASE, whatever you do, just don't get a Jeep cherokee or a Dodge durango type vehicle.  I see so many people driving those things around with horse trailers, and  it is just unsafe.) is starting cat fights.  towing is complicated enough without people handing out personal opinons or observations as fact....not to mention that  when pointing out what cant be done safely, when in fact it can, speaks loudly as to that indiviuals true experience.

well said.

since you appear to be only in the ~5000# loaded catagory ANY 1/2 ton would handle the trailer, a 1/2 ton set up to tow (v8, 4.1 rear, etc) would handle it easily. same for the tundra. no diesel is not necessary.

how used?  2004? 1994? there are too many variables there,  everyone will have their own preferences, if you dont know what youre looking at have a good mechanic give it a look.  id prefer not to be broken down with horses in tow.  when shopping for my truck i set my "limits" at 4yrs old, 75K. my truck is a 3rd vehicle, and basically only tows the trailer.  i am also in the same "usage" situation as you.

good luck.