What causes an auto trans to shudder at shifting RPM but not shift?

[lemming303]

OK yall, I was wrong. It is an FMX transmission. The door code on the car said FMX but the filter they gave me at O'reillys was the wrong filter. I took it back and told them the only other trans they were supposed to come with was a C4. I also looked at a transmission identification diagram and thought it was a C4. Apparently the pan gasket is the same for a C4 and an FMX. But the first kit they gave me at O'reilly had a totally different gasket and was the completely wrong filter. Anyway, that's just confusion. I found a pic of the filter on Ebay, I don't know how long it will be on there.

I apologize for the confusion yall. I guess I should have done more research and also made sure the guy at O'reilly was right. Anyway, does that change anything about my question? Again I'm sorry for the confusion. I told yall I don't know much about transmissions.

http://cgi.ebay.com/ebaymotors/FILTER-KIT-FMX-BRASS-1968-81-FORD-TRANSMISSION-SALE_W0QQcmdZViewItemQQ_trksidZp3286Q2em20Q2el1116QQhashZitem260381841738QQitemZ260381841738QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

[tactransman]

No, a FMX pan gasket and a C-4 are NOT the same.

FMX


C-4



Yes,the filter shown on E-bay is an FMX filter.

The modulator principle applies to an FMX also.

An FMX MUST be at the full mark on the dipstick to function properly.
 

[lemming303]

OK, I was wrong again. They looked the same when I glanced at them. I'm pretty sure it is an FMX now though. Thanks for your help. I'll post again once I get it checked out.