Start here: the price isn't the price
If you're comparing commercial generator distributors and your spreadsheet has one column for unit cost, you're comparing the wrong number. The number that decides whether the deal is good is the one that shows up 90 days later: the parts lead time, the private-label tooling bill, the commissioning window you never budgeted for.
Ask any supplier what's not included before you ask what it costs. If they can't answer that in one sentence, the quote is a teaser, not a quote.
That's the entire guide, compressed. Everything below is just reasoning.
Why I'm writing this from the order desk, not the sales desk
I coordinate emergency and rush orders at an electrical equipment distributor. We handle diesel and gas gensets — standby, portable, mobile — plus private-label OEM builds and the parts that keep them running. Over 9 years I've processed roughly 400 rush orders. Maybe 380 — I'd have to open the system — but the point is I've seen the same three problems repeat often enough that I no longer consider them bad luck.
Typical situation: a client calls at 9 a.m. needing a specific Caterpillar generator config for a job that starts in five business days. Normal lead time on that platform is 4 – 6 weeks. We're already in emergency mode. And the client's first question is almost always "what's the unit price" — when the question that would actually save them is "what does the entire delivery look like, start to finish."
Rush orders are my job. Which means I've mostly learned how standard orders work by watching them fail.
Three things the catalogue PDF never shows you
The catalogue is useful. It gives you the ratings, the fuel type, the enclosure options, the voltages. What it doesn't tell you is what deciding actually looks like.
1. Private label has a tooling timeline, not just a discount
When buyers ask about diesel generator private label, they usually mean one of three things, and the catalogue treats them as identical.
Custom nameplates and decals: 2 – 3 weeks, relatively cheap, low risk.
Custom control panel wiring or enclosure modifications: 6 – 10 weeks, and it requires a signed-off drawing set before the order begins — not after.
Full private-label OEM spec, where you're the manufacturer of record: 12 – 16 weeks of runway and a minimum order quantity that usually lands somewhere between 5 and 10 units, depending on the platform and whether it's a stock Caterpillar frame or a custom build.
Here's the part people underestimate: if you approve the drawing late, the tooling clock doesn't start when you thought you ordered. It starts when the drawings are signed. I watched a 10-week private-label build turn into 16 weeks last year because the buyer's engineering team spent 6 weeks on a single revision cycle (which, honestly, felt like two engineers arguing about a label font).
2. "Lead time" is three different numbers
Every distributor gives you one lead-time number. It's almost always the most optimistic one. What you actually need is:
- Build time — order to the unit rolling off the factory floor.
- Freight time — transit, customs, staging at your site.
- Commissioning time — site prep, fuel, exhaust, connection, and the local inspector's sign-off.
For a mid-size commercial unit, build might be 4 weeks. Freight might be 2. Commissioning might be 3 – 4 once everything's staged. So a "6-week lead time" can meet a 12-week deadline and blow a 9-week one without a single person lying to you.
I've learned to ask for all three separately, in writing, and to assume the build number is calculated without drawing changes, holidays, or a single substituted component. That said, this varies quite a bit by platform — a stock mobile unit and a custom standby set are almost different products, and the timelines don't transfer.
3. The parts pipeline question
This is the one that matters most and gets asked least. If you buy 20 gensets, the question isn't "will they run." They'll run. The question is: when one throws a fault in month 14, how many days until parts are on site?
Two things drive that answer: whether your distributor stocks parts locally or drop-ships them from the factory, and whether the specific platform you bought sits on a parts catalogue that's actually current.
A Caterpillar diesel generator is a Caterpillar diesel generator, but the parts ecosystem around it isn't automatically fast. Global parts networks exist — but the gap between "network exists" and "someone has an injector in a warehouse two hours away" is real, and it's the gap that costs you production hours. Even the ancillary costs creep in quietly (like lift rental, after-hours inspection fees, and a second crane if the first one can't reach the pad).
Ask specifically: "What's your average parts lead time on this platform, in our region, over the last 12 months?" Not the average across everything. Not the best case. The last 12 months, on this platform.
The FTC's advertising guidelines require supplier claims to be truthful and substantiated — the same standard you should apply privately to any lead-time or availability promise you hear, because in B2B there's nobody checking on your behalf.
The order that made me ask about commissioning up front
In March 2024, a client called 36 hours before a site switchover. They needed a mobile diesel unit delivered and running. Normal turnaround for that setup is 3 weeks. We had 36 hours.
We found the unit, paid $4,200 in rush freight on top of the $28,000 base, and delivered with about 4 hours to spare. The client's alternative was a penalty clause on their site contract — the number they quoted us was $50,000.
But here's the part I actually remember: we almost blew it on commissioning, not freight. The unit arrived on time. The site electricians were booked for the following week, because nobody had confirmed them the same way we'd confirmed the unit. We got lucky — a crew freed up. So glad we pushed on it, because we were one scheduling conflict away from delivering a generator nobody could legally connect.
Looking back, I should have asked about the electrician schedule before I asked about the freight. At the time, "get the unit there" felt like the whole job. It wasn't.
When this advice doesn't apply
If you're buying a single portable unit off the lot, most of this is overkill. If you're doing fleet replacement with a fixed config and you've bought the same unit before, the catalogue is honestly fine.
Where it matters is the moment you're doing anything new — new private label, new platform, new deadline, new region. That's where the spec sheet stops being useful and the questions start.
And if a distributor opens with their price and never gets around to what's excluded, that's not a red flag by itself. It's an incomplete sales conversation. You can finish it yourself with one question.