Some details are lacking here that might affect things. In particular, is this a straight pension (where they literally pay you a set amount), or do they contribute this amount to a pension fund, invest it, and pay you from the investment earnings? And in either option, does how long you survive affect your earnings from the pension?
At the simplest, though, I think you should consider how much you would need to save for your retirement if you didn't have the pension. Estimate how much you'd put away and then invest in order to end up with roughly the same amount per year in the future. If the pension is a direct rate (so $16,500/yr), and let's say you expect to live to 75 (so 10 years of retirement if it pays out at 65), then work out how much you'd have to save now in order to earn that $16,500*10=$165,000 in retirement income.
Let's say you compare that to the $55000 job as explained in Phil's comment. So you put away $5000 per year (the difference between the two jobs). If you're going to earn 5% annually on that $5000, a reasonably conservative figure, then you'll end up with that $5000 being worth around $13000 in 20 years (let's say you're 45 now). If the pension is also annual (so each year you work = one year at $16500), then that's a bit less, especially as you get a lesser multiplier for later years. The sum for 10 years (from age 45 to age 54) is almost $110,000, so you're earning about 30% less if you value dollar to dollar equally.
I'd consider that probably about equivalent to the pension personally (as it's slightly less money, but you have a lot more control and protection from the company's pension fund going bankrupt or whatnot), but it's up to how you see things. You'd have to earn almost $58,000 (and put away $8,000) in this scenario to come out ahead on a dollar to dollar basis.
Really, your age is the biggest factor when evaluating pensions. If you're 25, you have 40 years to go, and a lot of time to earn more. In that case, that $5000 is worth $35000 in 40 years - far more than it is if you've only got 20 years to grow, right? Also, you have far more concern about the company's or government's stability over that length of time.
On the other hand, if you're 55, a pension is appealing. You've only got 10 years for your investments to grow, and you're close enough that the risks of corporate bankruptcy or governmental instability is less significant.
Given the additional details, I think the above still largely applies - but I'll add a bit.
Since you're 23, first off, even a small salary difference will help you a lot more than that pension for the same salary. A $5000 difference for year 1 will be worth almost $40,000 when you're 65. A $2500 salary difference is almost $20,000 by 65. You'd have to be looking at more like a $2,000 difference to consider it equal - at the same salary.
Now, of course you will be getting 33% of your last five years with the company salary. On the one hand, that means you'll be getting more presumably - but it also ties you down to the company. That's more significant than you'd probably think.
One of the main ways a worker gets a salary increase is by switching companies. It's very common after the first five or so years (where you get decent raises, usually) to have fairly stagnant pay relative to inflation, even for exceptional workers - unless you're C-level, anyway. Particularly if you're not moving into management proper, you'll need to change companies periodically to keep your salary rising as high as it's possible to.
Pensions exist largely to discourage that movement. Since you'll gain 3% or so per year anyway, let's say you start at $75000 5 years from now, and increase at 3% per year after that. Your salary at retirement will be somewhere in the $200k range. You might not actually get that due to caps, and remember we're only keeping a bit ahead or even with inflation here so it's not really that much more than $75k in present dollars, but the idea is there: you'll earn a lot more in 30-40 years than you do now, meaning your pension will be a lot higher.
But, if you leave after 10 years, you'll only be around $85k. That makes that pension worth far less, right? Hence the disincentive to move. You also probably have a vesting schedule, which may require 5 to 10 or even more years' service before you earn that full 33%. So who knows what you're actually going to get from this pension. Add to that - you don't have any idea if you'll fit well in the culture.
That said - it could well be that you get a quite decent amount of money out of this. Certainly it's worth something, even if you don't stay all that long. You should take this over an equivalent job with the same salary and same other benefits, because it's worth something. It's very hard to impossible to quantify all of this, because there are too many variables. It's simply too hard to figure out what your salary will be in 40 years if you stay there vs. if you move to another company.
My recommendation would be to assume the pension is on this year's income level, and thus act as if it's worth $16k/year for life (which is around 10 years on average). Then work backwards to the value of any particular salary differential, and that's your value. That makes it worth about 4.5% of your salary now (using A=P*(1+r)^t, solving for P where A=33% and r=5% annual growth). That's what I'd value it at.
