The standard diff ratio in a Ute is 4,11 to 1 & was intended to help the short stroke, low torque 1200 engine to haul the full rated load that a ute is designed for.

The A14 engine has a 7mm [1/4" longer stroke as well as a larger bore & it develops a very useful increase in torque.

If the Ute is to be used as a toy rather than as a workhorse then a switch to the 3.9 to 1 ratio found under most L series powered models [with live rear axles] will cut the revs without hurting performance noticeably.

Using a tyre with an outside diameter of at least 575mm is also a good idea. I recomend 205x60x13's on the rear as these will help fill the wheel well without rubbing & are readily available at modest cost.
A 6" wide rim is perfect for this size tyre.

The five speed sounds good but is both difficult to obtain & expensive when found, but in addition to the above alterations, it would be recomended because at highway speed in 5th the little sucker will be singing sweetly.

For international members the legal highway speed in most areas over here is 70mph [110kph] not 55 mph [88kph]& I have never been 'pinged' at 5kph over [73mph] which is a fair clip for a little Datsun to sustain.

Haha ok yer the a14 loves screaming down the freeway the 5 speed seems the way to go but for the meantime I already have it on 13" alround on 185/70 tyres so taller in the rear? Thanks for the advice

Definitely go with the 5-speed overdrive. It will keep your 1st gear ratio, but reduce revs at speed. Changing to a 3.x ratio will reduce your acceleration performance.

Keep in mind that 3500-4000 rpm is normal -- It won't hurt the A14 at all. But the overdrive will lower noise and improve fuel-economy.

They're a bit noisy aren't they? It won't hurt anything except your sanity as thats the way they always were.

Taller diff ratio is cheaper but blunts the in gear performance. Maybe a better alternative might be some 13" wheels all round with some taller tyres on the rear?

Hey guys I have a 71 1200 ute with a 4 speed and I have rebuilt the a14 my problem is that the gears are really short and at 60mph it's doing about 3600-3700 rpm. So I was wondering should I be looking at a 5speed or changing to a higher ratio diff? Cheers