Can I use a safety thermostat that's L200-70f even though the one that was in it is L180-40f

I wouldn't. I don't know what the numbers mean but if I had to guess I would guess that the original came on at 40 and shut off at 180. Therefore the L200-70 would be on at 70 and off at 200. You can see the problem.

Why not get the correct part?

Try here:
Click Dryer Parts, Frigidare and so on:
Appliance Parts Pros.com Discount Appliance Parts ? Appliance Repair Parts

Well for one thing there's about a 70 dollar price difference and when I talked to my local repair shop they say it cross refs with a L285-70f so I thought if it could be over by 105 why can't it go over by 20 and I can save some money because the L180-40f sells for around 77 to 97 dollars and the L200-70f sells for $8.60 so you can see why I would like to know if I can use it

Is this it:
36T21 11569 L180-40F - N.Closed 15Amp Thermal disc

$3.95?

Someone is trying to rip you off because that t-stat is cheap. DrTom4444

Well stratmando that's not it but thanks for looking and drtom4444 I don't think anyone is trying to rip me off these are the prices I have found on the web the L285-70f that my local repair shop is trying to sell me is $21.00 I have a part number if that would help its 5308015399 and like said I have found it from $69.00 to $97.00 I am just trying to save some money because I have found every other one for much less any help would be greatly appreciated

May just be an expensive item:
FRIGIDAIRE 5308015399 Sfty Thermostat, AP2152884 | AppliancePartsPros.com

What is model number of dryer?

You can call the Frigidaire parts' line @ (800) 599-7569 and place a direct order. Since they are direct suppliers, they should be able to quote you baseline price. Just be sure to have your unit model number on-hand when you place the order. Hope this helps!

Best of luck!

Chris Polk
Online Outreach Representative

Ok the model number is fridgidaire FDG648GHSO it looks like ill have to pay the 70 plus dollars for it I was hopeing someone could tell me for sure if I could use the L200-70f in its place but thank you to all who tried to help

Does it look like the one on my 7:17 Post, can you provide Model of Dryer?
Sounds like you want to use a different part because it is cheaper, If it works it would be a great savings.
They call it a Safety Thermostat, likely for a reason, A different part may? Be less safe?

OK I tested the safety thermostat on a digital multimeter set at 200 oms and it reads 01.0 and if I hold it there for a few it reads 00.9 so is the part still good or is it bad thanks

It is good. DrTom4444